Annotations are meta-data about whole or part of a knowledge resource in the form of comments, notes, explanations, or other types of characterization. These are created either manually or semi-automatically. These annotations are update, stored and share with others.

As Annotations are external, it is possible to annotate any knowledge resource independently, without needing to edit the resource. Annotations can be stored locally or in one or more annotation servers. These annotations are meta-data, as they give additional information about an existing knowledge resource.

This service includes a creation, updation, deletion of annotaions created by the members of the CITK system. These annotations are also shared among the users of the system.
Sharing content through Web pages is important but also is limited as readers can seldom share comments or questions by writing back to the pages, even when they are members of a closed collaborative group. Instead, with the Web today we still observe much effort spent by users on forming and trying to understand different e-mail conventions for commenting on documents that are on-line in the Web.

Shared annotations that do not require write access to the annotated page can support very rich communications about the Web pages. When these annotations are seen as metadata about the pages or parts of them, and when the metadata vocabulary is grounded in semantically rich ontologies that are themselves published in the Web, a lot of possibilities that extend beyond basic annotation capabilities are opened.

Annotaions can be created for the knowledge resources available in the system. One can also annotation their own knowledge resources by uploading them. These annotations are created manually or semi-automaticalyl. One can define annotaion schema for annotating the knowledge resources. Annotaions also has meta-data for defining type schema. Annotaions can be stored in a file format or to a database server.

RDF Schema is used to represent annotaion types and annotaions. The generic property mechanism of RDF allows us to construct ontology-neutral data stores. Applications can use several ontologies simultaneously to describe different aspects of their annotations. The RDF model provides a convenient mechanism on which to layer client-side or server-side inferencing for mapping between ontologies.