Web Design in a Nutshell, 3rd Edition

Deleted and Inserted Text

The ins and del elements are used to mark up changes to the text and indicate parts of a document that have been inserted or deleted (respectively). They may be useful for legal documents and any instance where edits need to be tracked.

As HTML elements, ins and del are unusual in that they may be used to indicate both block-level and inline elements. They may contain one or more words in a paragraph or one or more elements like paragraphs, lists, and tables. When ins and del are used as inline elements (as in within a p), they may not contain block-level elements because that violates the allowable content of the paragraph.