is for the Elisp advice feature that changes an existing definition of a function in a way that lets you undo the change easily. This tag applies to both old and new advice features. The old advice feature uses `defadvice`. The new advice feature uses functions and macros such as `advice-add` and `add-function`.
While the tag is properly spelled as the noun advice, the Emacs manuals and Stack Exchange questions also use
advise(the verb form) and
advising. Try these alternate spellings when searching.