This may be used, for example, to indicate text deleted in the course of editing. Both the ulem and the soul packages provide the necessary facilities.
Overstriking with an “attached” comment may be achieved using the pdfcomment package, to which you can give optional arguments with all sorts of detail. The comment text is encoded using an Adobe ‘annotation’; unfortunately, support for these annotations is not a common feature of PDF viewers, but if you can safely assume that your audience will use Acrobat Reader, the facility provides that extra “shine” that business users so love.
Overstriking for cancellation in maths expressions is achieved by a different mechanism.
Documentation of ulem is in the package file.
This answer last edited: 2013-08-29