Text annotation: prepare NLP and LLM data


Text annotation and AI: how a simple label is revolutionizing text data processing
Text annotation is a key process in the development of artificial intelligence models, especially those specialized in natural language processing (NLP). By combining accurate labels with text and text segments, data set preparation teams (otherwise called “annotators” or “Data Labelers”) provide algorithms with the information they need to understand, interpret, and process textual data effectively.
This work, which is often invisible to the end user, is nevertheless one of the fundamental steps in the creation of intelligent applications such as chatbots, search engines or even machine translation systems.
Text annotation is a key process in the development of artificial intelligence models, especially those specialized in natural language processing (NLP). Having text annotated by human annotators is crucial for creating high-quality training data for NLP and machine learning applications. By combining accurate labels with text and text segments, data set preparation teams (otherwise called “annotators” or “Data Labelers”) provide algorithms with the information they need to understand, interpret, and process textual data effectively.
This work, which is often invisible to the end user, is nevertheless one of the fundamental steps in the creation of intelligent applications such as chatbots, search engines or even machine translation systems. Manual annotation, where humans label or tag specific parts of text to ensure accuracy, is often used in this context, with tools like Tagtog facilitating the process through user-friendly interfaces.
NLP text annotation is a key step in preparing data for models specialized in natural language processing, enabling them to perform tasks such as voice recognition, sentiment analysis, and language translation.
A typical text annotation process involves several steps: data selection, labeling, quality control, and validation, often utilizing specialized tools to streamline the workflow and ensure consistency.
Text annotation thus plays an essential role in the ability of machines to learn and generate consistent responses, while allowing AI models to process massive volumes of data with ever greater precision in order to learn and improve.
💡 In this article, we explain in detail how text annotation, this stage of preparing training data for AIs, makes it possible to develop efficient AIs !

What is text annotation and why is it essential for AI?
Text annotation consists of assigning labels or tags to texts, in particular to segments of text within the same document, in order to structure and enrich the raw data. This process allows artificial intelligence (AI) models, especially those specialized in natural language processing (NLP), to understand textual content more precisely, by interpreting these indications (metadata). Key concepts can be extracted from textual information using keyphrase tagging, which helps identify the main ideas discussed in a document. Semantic annotation and entity annotation are advanced techniques for labeling concepts and entities in text, further enhancing the structuring of data.
For example, annotation may include the recognition of named entities (people, places, dates), the classification of emotions, or the segmentation of sentences according to their grammatical function. Text annotation can involve different categories such as sentiment analysis, named entity recognition, and document classification. Linguistic annotation involves detailed labeling of text for research and NLP applications, providing deeper insights into language structure. Language identification is another type of annotation that determines the language of a given text. Highlighting is often used to emphasize important segments, while making notes or adding a note can provide supplementary information or commentary.
Text annotation is essential for AI because it provides a structured learning base that allows models to identify Patterns and to understand the nuances of human language. Annotators can start annotating by setting up projects and uploading data, following an annotation workflow that includes steps like data selection, labeling, and validation. Annotation tools allow users to annotate texts and annotate data efficiently, enabling them to create annotations, make notes, and share notes with others. Collaborative annotation is enhanced by seeing others annotations and the contributions of other readers. Without accurate annotations, models would be unable to interpret linguistic subtleties, which would affect the performance of tasks such as machine translation, sentiment analysis, or text generation. Annotated data is used to train machine learning models for various NLP applications. When labeling, a given text is analyzed to extract key information or assign categories. Advanced annotation methods such as entity linking connect recognized entities to a knowledge base, improving disambiguation and context.
Annotating research articles can also improve AI models by providing rich and varied data, which enhances their ability to process complex information and generate more accurate answers.

The annotation process: from raw text to labeled data
The annotation process is the backbone of preparing textual data for machine learning models, especially in natural language processing. It transforms unstructured text into structured, labeled data that algorithms can learn from. The journey begins with collecting raw text data, which may come from sources like customer feedback, social media, or business documents. This raw data often contains noise—unnecessary characters, formatting, or irrelevant information—which is removed during pre-processing to ensure clean input for annotation.
Once the text is pre-processed, the next step is to use a text annotation tool, such as doccano or brat, to assign meaningful labels to specific parts of the text. These labels might include named entities, key phrases, sentiments, or other relevant categories, depending on the goals of the annotation process. The annotation tool provides an interface for annotators to highlight text segments and apply the appropriate tags, making it easier to create consistent and accurate annotations.
After the initial round of annotation, the annotated data undergoes a review and validation phase. This step is crucial for ensuring that the annotations are consistent, accurate, and aligned with the project’s objectives. Any discrepancies or errors are corrected, and the final annotated dataset is compiled.
The result is a high-quality, labeled dataset that can be used to train and test machine learning models. These models, in turn, learn to recognize patterns, extract key information, and make predictions based on the annotated data. By following a structured annotation process, organizations can create robust datasets that power advanced natural language processing applications and drive better business outcomes.
How does text annotation contribute to the improvement of natural language processing (NLP) models?
Text annotation plays a fundamental role in improving natural language processing (NLP) models by providing rich and structured training data. High-quality text annotations are essential for training effective NLP models, as they help capture the nuances and complexities of human language. NLP models, who seek to understand, generate, and analyze human language, rely heavily on these annotations to learn the complex relationships between words, sentences, and their meanings.
Here are some specific ways in which text annotation contributes to the training and development of AIs:
- Annotating a text supports reading comprehension and active reading, especially in educational or collaborative settings, by encouraging deeper engagement and understanding of the material.
- Accurate annotation helps ensure that the data used to train models is reliable and relevant, which is critical when you annotate data for machine learning applications.
Enrichment of training data
Annotations provide NLP models with additional information that allows them to better understand the context and relationships between text elements. This includes annotations for syntax, semantics, relationships between entities and intents, as well as annotating each line of text using specific tools, which are essential for tasks like sentiment analysis or the recognition of named entities.
Accuracy improvement
By annotating texts with specific tags (e.g., entity labels or grammatical category labels), models learn to distinguish the different meanings of a word or to better interpret the context. This reduces ambiguities and improves the accuracy of model predictions.
Reducing bias
By using annotated text data from a variety of sources, NLP models can be trained to be less biased and to provide more fair and equitable results. Annotation also makes it possible to identify and correct potential biases in the data.
Customizing templates
Manual or semi-automated annotation makes it possible to create textual data sets specific to particular fields (such as medicine, law, etc.), allowing NLP models to adapt to the linguistic requirements of these sectors and thus improve their performance in specialized tasks.
What are the different types of text annotation used in AI?
There are several types of text annotation used in artificial intelligence, each with a specific role in improving the understanding and processing of natural language by models. Text annotation is applied across different categories and use cases, such as fraud detection in finance, extracting loan rates from documents, and analyzing public opinion through sentiment analysis. Here are the main types of text annotation:
Annotating named entities (Named Entity Recognition, NER)
This type of annotation identifies and marks entities in text, such as people, places, organizations, dates, etc. For example, in the sentence”Barack Obama was born in Hawaii“,”Barack Obama“would be annotated as a person and”Hawaii“like a place. This allows models to recognize entities that are important in different contexts.
Sentiment annotation (Sentiment Analysis)
Feeling annotation consists in classifying the emotions or the attitude conveyed by a text (positive, negative, neutral). For example, a product review can be annotated to indicate whether the feeling expressed is favorable or unfavorable, helping models understand the tone and opinion.
Annotating parts of speech (Part-of-Speech Tagging)
This type of annotation assigns a grammatical category to each word in a sentence, such as verb, noun, adjective, etc. This helps models analyze sentence structure and understand the function of each word in the context.
Intent annotation (Annotation Intent)
This type of annotation identifies the underlying intent of a sentence or text, for example, a request for information, a service request, or a complaint. This is especially useful in chatbot and voice assistance applications, where it is essential to determine its use, whether for businesses or individuals.
Text segmentation annotation (Text segmentation)
This type of annotation consists of dividing text into logical units such as sentences, paragraphs, or thematic sections, by creating new paragraph marks when segmenting the text. It allows models to analyze text into more coherent blocks for text summarization or comprehension tasks.
Classification of documents (Document Classification)
Annotation for document classification consists in assigning one or more categories to texts or entire documents. A context menu can be used in annotation tools to facilitate the classification of documents by offering various configuration options related to the annotation schema. For example, an article can be classified as a technology, finance, or health article, depending on its content. This is essential for recommendation or search systems.
Annotating complex linguistic elements (Coreference Resolution)
This type of annotation identifies words or phrases that refer to the same entity in a text. For example, in”Marie picked up her book, she will read it later“,”she“refers to”Marie“. Annotation helps models understand relationships between different text elements.
Dependency analysis annotation (Dependency Parsing)
This annotation identifies grammatical relationships between words in a sentence, by marking dependencies between a main word (usually a verb) and its complements or modifiers. This helps models understand the syntactic structure of sentences.
Translation annotation or alignment
When text is translated from one language to another, each text segment is aligned with its corresponding translation. This is used to train machine translation models to improve their ability to provide accurate translations.
💡 These types of annotation allow textual data to be structured and enriched for more efficient AI models, capable of understanding texts in a more nuanced way and of performing complex tasks related to natural language.
Collaborative annotation and guidelines: ensuring consistency and quality
Collaborative annotation is essential for producing high-quality, reliable datasets for machine learning models. When multiple annotators work together on the same dataset, it’s vital to ensure that everyone applies labels and annotations in a consistent manner. This is where clear annotation guidelines come into play.
Annotation guidelines serve as a reference manual for annotators, outlining the definitions of each label, providing concrete examples, and specifying how to handle edge cases or ambiguous situations. For instance, guidelines might clarify how to annotate overlapping entities, how to distinguish between similar categories, or what to do when a text segment could fit multiple labels. By standardizing the annotation process, guidelines help reduce subjectivity and ensure that the resulting annotations are uniform across the dataset.
Regular communication is also key in collaborative annotation. Team meetings, discussion forums, and feedback sessions allow annotators to share questions, resolve disagreements, and refine the guidelines as needed. When annotators encounter uncertain cases, they can consult with others or escalate the issue for group discussion, ensuring that the final decision is documented and applied consistently going forward.
By fostering a collaborative environment and adhering to well-defined annotation guidelines, teams can create high-quality, consistent annotations. This not only improves the accuracy of machine learning models but also streamlines the annotation process, making it easier to scale up and tackle more complex natural language processing tasks.
Data quality and active learning in text annotation
High data quality is the foundation of successful machine learning models, especially in natural language processing. Poorly annotated data can lead to inaccurate predictions, biased outcomes, and unreliable AI systems. To address this, active learning has emerged as a powerful strategy for improving both the efficiency and quality of the annotation process.
Active learning involves training an initial machine learning model on a small set of annotated data, then using the model to identify the most informative or uncertain samples in the remaining dataset. These samples are prioritized for annotation, ensuring that human effort is focused where it will have the greatest impact on model performance. As new annotations are added, the model is retrained, and the cycle repeats until the desired level of accuracy is achieved. This targeted approach reduces the total amount of annotation required while maximizing the value of each annotated example.
In addition to active learning, other techniques can further enhance data quality. Data augmentation generates new samples by modifying existing ones—such as paraphrasing sentences or swapping synonyms—helping to create a more diverse and robust dataset. Data normalization ensures that all data is scaled and formatted consistently, reducing variability that could confuse machine learning models.
By combining active learning with rigorous quality control and data enhancement techniques, organizations can create high-quality annotated datasets that drive superior results in natural language processing and other machine learning applications.
Annotation process optimization: making annotation efficient and scalable
Optimizing the annotation process is essential for handling large-scale projects and meeting the growing demands of machine learning models. Efficiency and scalability can be achieved by blending automation with human expertise, leveraging the strengths of both to create high-quality annotated data.
One effective strategy is to use automated tools, such as named entity recognition (NER) models, to pre-annotate the data. These tools can quickly identify and label common entities or patterns, providing a first draft of the annotations. Human annotators then review and refine these pre-annotations, correcting errors and handling more complex or nuanced cases that require human judgment. This collaborative approach speeds up the annotation process while maintaining high standards of accuracy.
Active learning can further streamline the workflow by selecting the most valuable samples for annotation, ensuring that human effort is focused where it matters most. Annotation guidelines and user-friendly annotation interfaces also play a crucial role, providing clear instructions and intuitive tools that help annotators work efficiently and consistently.
For organizations looking to scale up, advanced techniques like transfer learning and few-shot learning can be leveraged. These methods allow pre-trained models to be adapted to new tasks or domains with minimal additional annotation, reducing the time and resources required to create effective machine learning models.
By continuously refining the annotation process—combining automation, active learning, clear guidelines, and advanced learning techniques—organizations can efficiently annotate large datasets, improve data quality, and accelerate the development of powerful natural language processing solutions.
Text annotation: what are the benefits?
Text annotation has many advantages for preparing datasets used for training artificial intelligence models. Here are some of the main benefits:
- Improving the accuracy of AI models : By annotating texts, artificial intelligence models can be trained on high-quality data, improving their ability to understand and interpret natural language.
- Automating repetitive tasks : Text annotation makes it possible to automate repetitive and time-consuming tasks, such as classifying documents, extracting information, and generating summaries.
- Customizing services : Businesses can use text annotation to personalize their services based on user preferences and behaviors, improving the customer experience.
- Sentiment analysis and public opinion : Text annotation makes it possible to analyze the feelings expressed in the texts, which is useful for market research, reputation management, gauging public opinion, and strategic decision making. This helps businesses develop effective strategies and track brand perception over time.
- Anomaly detection, fraud detection, and finance applications : By annotating texts, anomalies or suspicious behavior can be detected, which is critical for security and compliance. In the finance industry, text annotation is also used for fraud detection and extracting key information such as loan rates to streamline processes and reduce manual labor.
- Supporting reading comprehension and active learning : Text annotation enhances reading comprehension and active learning, especially in educational contexts. Making notes, adding a note, and sharing notes as annotations help students and other readers engage with the text, improve memory, and develop critical thinking skills. Collaborative annotation allows exposure to others annotations, which further supports understanding and learning through peer insights.
Text annotation tools
There are numerous text annotation tools available on the market, each offering specific features to meet the varied needs of users. Many of these tools support manual annotation, providing an intuitive annotation workflow that streamlines the process and ensures high-quality results. Some platforms also make it easy for users to start annotating by offering simple onboarding processes, such as account creation or license key activation. Here are some of the most popular ones:
- Prodigy: A text annotation tool that allows the creation of annotated data sets in a collaborative and efficient manner. It is especially useful for text classification and entity extraction tasks.
- Labelbox : A data annotation platform that offers advanced features for annotating text, images, and videos. It is used by many businesses to train AI models.
- Doccano : An open-source text annotation tool that allows creating annotated data sets for natural language processing (NLP) tasks. It is easy to use and can be deployed locally or on the cloud.
- UbiAI : A text annotation platform specialized in natural language processing. ubiAI combines an intuitive interface and automated features to speed up the annotation of textual data and reduce human errors.
- Tagtog : A text annotation platform that offers advanced features for document annotation, project management, and team collaboration. It is used by companies and researchers for NLP tasks.
Use cases for text annotation in AI
Text annotation is an important component in many artificial intelligence (AI) use cases. Here are a few examples:
- Chatbots and virtual assistants : Text annotation makes it possible to train chatbots and virtual assistants to understand and answer user questions accurately and contextually.
- Sentiment analysis : Businesses use text annotation to analyze the feelings expressed in customer reviews, social media comments, and satisfaction surveys.
- Detecting spam and inappropriate content : Text annotation makes it possible to detect and filter spam, inappropriate content, and suspicious behavior on online platforms.
- Information extraction : Businesses use text annotation to extract relevant information from documents, reports, and databases, which is useful for knowledge management and decision making.
- Machine translation : Text annotation improves the quality of machine translations by providing examples of sentences and words that have been correctly translated.
Challenges and limitations of text annotation
Annotating text has several challenges and limitations, including:
- Linguistic complexity : Natural languages are complex and have many nuances, ambiguities, and regional variations, making text annotation difficult and error-prone.
- Data volume : Annotating large volumes of text can be time-consuming and expensive, requiring human resources and specialized tools.
- Quality of the annotations : The quality of annotations depends on the skill and rigor of the annotators, which can vary and affect the accuracy of AI models.
- Evolution of languages : Languages are constantly evolving, with the appearance of new words, expressions, and uses, which requires regular updates of annotated data sets.
- Bias and subjectivity : Annotations can be influenced by the biases and subjectivity of the annotators, which can introduce biases into AI models.
Ethics and safety in text annotation
Annotating text raises ethical and safety issues, including:
- Confidentiality of data : Text annotation often involves the use of sensitive data, such as personal information and private communications, which poses privacy and data protection challenges.
- Bias and equity : AI models trained on annotated data can replicate and amplify biases in the data, which can lead to inequities and discrimination.
- Transparency and explainability : Users and regulators are increasingly demanding transparency and explainability in the processes of annotating and training AI models, in order to ensure reliability and accountability.
- Data security : Annotated data sets should be protected from unauthorized access and cyber attacks, in order to ensure the security and integrity of the information.
Text annotation for AI use cases: yes, but for what future?
Since the end of 2022, LLMs have been at the forefront when it comes to text-based AIs. However, NLP models and text annotation are constantly evolving, with many trends for the future. Not every use case needs an LLM! Here are some of our predictions for using text annotation to build datasets:
- Increased automation... but humans at the heart of the data set creation process : Advances in artificial intelligence and the evolution of technological labelling solutions should make it possible to speed up the data preparation process. The future is more modest data sets (several thousand data against several hundred thousand) but of better quality, prepared by experts! Preparing a dataset is a job!
- Multimodal integration : Text annotation will increasingly be integrated with other modalities, such as images and videos, to create more complete and accurate AI models... A Data Labeler must master many types of annotation. In short, Data Labeling is a job!
- Ethics and responsibility : Ethical and security concerns will become increasingly important, with increased efforts to ensure the transparency, fairness, and protection of the data used to train the models.
- Technological innovation : New technologies and methods for text annotation will emerge, offering more advanced and more effective solutions for natural language processing tasks.
Text annotation is proving to be an indispensable step in the development of artificial intelligence models, especially those related to natural language processing. We tend to think that LLMs can do everything, but this is not true or even too expensive depending on your use cases. Preparing annotated texts to use them as datasets for various models indeed allows algorithms to understand and interpret textual data more precisely. This is the foundation on which many modern applications are based, whether chatbots, search engines or machine translation systems.
Each type of annotation plays an essential role in structuring the data, thus ensuring the quality and relevance of the models trained. As AI technologies continue to evolve, the need for accurately annotated data will only grow, underlining the continued importance of text annotation in the quest for better, more humane artificial intelligence.
However, annotating large files can pose challenges in terms of accuracy and quality, requiring specialized tools to ensure effective management... but above all experts who can manage data annotation processes at scale. Do you want to talk about it? Do not hesitate to contact us!