1. A system for redacting one or more portions of a document, the system comprising: at least one computer processor programmed to implement: a user interface enabling a user to select, from a first version of the document, a portion of the document, and to specify to redact the selected portion from the document; a redaction controller to control, in response to the user specifying to redact the selected portions a modifying of the selected portion in a plurality of versions of the document, wherein at least one of the plurality of versions is the first version; a save controller to save the first version of the document with the selected portion of the first version of the document being redacted; and an access rights controller enabling a user to specify a first group of one or more users with access rights to view content of the selected portion and a second group of one or more users without access rights to view content of the selected portion, so that, for each user in the second group, when at least one of the one or more versions is displayed, content of the selected portion in the at least one version is not visible to the user and is shown as being redacted; wherein the user interface is operative to enable the user to select, from the first version of the document, a plurality of redacted portions of the document, and to specify that the plurality of redacted portions be combined to form a single redacted portion, and wherein the redaction controller is operative to combine the redacted portions in each of the plurality of versions to product a single redacted portion in each version.