Annotation is the process of adding descriptive metadata or additional information to a document, dataset, or any other type of content. This can include labeling data points, adding notes or comments, identifying key features, or categorizing information for easier organization and retrieval. Annotation is commonly used in fields such as linguistics, literature, biology, and digital humanities to enhance the understanding and usability of research materials. It helps researchers to make sense of complex information, improve data analysis, and create more meaningful connections between different pieces of content.