15. A non-transitory computer readable medium having instructions stored thereon that, when executed, cause a processor to: obtain a first collection of source files; for each source file in the first collection: parse the respective source file to extract one or more tags, compare the one or more tags to tags in at least one dictionary to determine one or more matching tags, wherein the at least one dictionary comprises a hierarchical listing of tags, and associate, with the respective source file, the one or more matching tags; generate a first virtual relational network comprising the source files in the first collection, wherein the first virtual relational network comprises: one or more nodes, wherein each node of the one or more nodes represents a particular matching tag of the one or more matching tags associated with a particular source file of the source files in the first collection, and one or more links, wherein each link of the one or more links represents a connection between a pair of nodes, wherein each node of the pair of nodes is associated with a same tag; compare the first virtual relational network to a second virtual relational network to identify at least one of (a) nodes common to the first and second virtual relational networks, and (b) links common to the first and second virtual relational networks, wherein the second virtual relational network is created from a second collection of source files different from the first collection of source files, and the second virtual relational network is created using one or more dictionaries of the at least one dictionary; and display a graphical representation of at least part of the first and second virtual relational networks.
22. The non-transitory computer readable medium of claim 15 wherein the first collection of source files is associated with an entity at a first time, and the second collection of source files is associated with the same entity at a later time.