1. A computer implemented method of providing a navigation topology in a portal supporting a social network, said method comprising: annotating portal resources; wherein said portal resources are uniquely identifiable fragments; wherein said portal resources comprise one or more of the following: page, portlet, user, email, wiki, blog post, or applet; wherein said annotation is performed by a user, or is performed automatically by extracting some data from first portal resources among said portal resources visited by said user; an automated bot annotating said portal resources; storing said user generated annotations and said bot generated annotations in an annotation store accessible by a plurality of different annotators; tracking said user's annotating behavior, based on all annotations applied to said portal resources which said user visits or uses; deriving a user model based on all users' annotating behavior, said all users' preference and interest, and said all users' profiles, using a web mining method; wherein said web mining method comprises at least text mining; assigning said user to a group model based on said web mining method and recommending changes made by a specific fraction of other group members of said group model to said user; deriving a context model based on one or more of factors; wherein said one or more of factors comprise one of said user's annotating behavior, timing of resource annotations, a device said user is working with, and a location of said user; determining similarities and relationships between said portal resources and tags, by calculating a semantic distance between said tags and said portal resources; partitioning said user model into a sole partition for each context profile available in said context model; automatically determining a matching profile, by observing a set of predefined context attributes; wherein said user has an option to override said matching profile; dynamically adopting a navigation topology for each of said all users, by generating a tree model at run time, based on behavior of said each of said all users and current context; wherein a tag-driven structure has a minimum click distance between content elements that are annotated; wherein said navigation topology comprises a dynamic node; wherein said dynamic node is associated with a transformation; wherein said dynamically adopting said navigation topology comprises constructing a topology by traversing said tree model, and invoking said transformation; wherein said transformation performs its specific operation to generate a sub-model; wherein said specific operation comprises one of moving or hiding navigation tree nodes depending on their relevance; wherein said sub-model is phased into said navigation topology, directly underneath said dynamic node; and displaying said constructed topology to said user.