Clippy was enabled by default in some versions of Microsoft Office, and came to be hated by many users. It would pop open whenever the program thought the user could use its advice, and frequently either the advice was not really required or it was not really useful. One of the key elements of Microsoft's advertising campaign for Office XP was the removal of Clippy and the Office Assistant from the software, although it was still present, providing the user enabled it.
Other animated representations other than the paperclip were available, but the default paperclip is the most widely known.