When on, all ' (single-quote), "
(double quote), \ (backslash) and NULL
characters are escaped with a backslash automatically. This is identical
to what addslashes() does.
There are three magic quote directives:
magic_quotes_gpc
Affects HTTP Request data (GET, POST, and COOKIE). Cannot be set at
runtime, and defaults to on in PHP.
See also get_magic_quotes_gpc().
magic_quotes_sybase
If enabled, a single-quote is escaped with a single-quote instead of a
backslash. If on, it completely overrides
magic_quotes_gpc. Having
both directives enabled means only single quotes are escaped as
''. Double quotes, backslashes and NULL's will
remain untouched and unescaped.
See also ini_get() for retrieving its value.