Font Lock mode is a buffer-local minor mode that automatically
face properties to certain parts of the buffer based on
their syntactic role. How it parses the buffer depends on the major
mode; most major modes define syntactic criteria for which faces to use
in which contexts. This section explains how to customize Font Lock for
a particular major mode.
Font Lock mode finds text to highlight in two ways: through syntactic parsing based on the syntax table, and through searching (usually for regular expressions). Syntactic fontification happens first; it finds comments and string constants and highlights them. Search-based fontification happens second.