This document discusses WordPress filters and provides examples of how they can be used. It begins by defining a filter as a function that takes a WordPress value, optionally modifies it, and returns the resulting value. It then explains the apply_filters() function and lists over 1,300 filter hooks in core. Examples are given for using filters to modify content in the editor, customize admin menu ordering, filter meta boxes and post types when deleting users. Front-end filters discussed include modifying post content, body classes, and excerpt length. The document concludes with filters useful for development like modifying plugins/themes listings and enabling post by email.