1. At least one computer-readable storage medium having computer-executable instructions stored thereon which, when executed by a computer, cause the computer to perform a method comprising: receiving at least one document from a server, wherein the server is for communicating with a plurality of client systems that are remote from the server; receiving an indication of at least one revision to the document, as provided by a first user interacting with one of the client systems; determining automatically whether to capture a representation of a state of the document before entry of the revision, without an explicit user command to capture the representation; and capturing the representation of the state of the document in response to determining that the revision alters existing content added previously to the document by at least a second user.