A management module of an annotation server receives annotation data, which contains location information of web page data, content information of an annotation, and position information of an object to which the annotation is linked, from a web client machine together with a registration request. Then, the management module issues an annotation ID. The module retrieves a text, which consists of an object to which the annotation is linked and an adjacent part that has a relationship satisfying a predetermined condition with the object, as context information from a source text of the web page. Then, the module registers the context information together with the annotation data that is received in advance into an annotation database.
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