PHP transparently supports HTTP cookies. Cookies are a
mechanism for storing data in the remote browser and thus
tracking or identifying return users. You can set cookies
using the setcookie() function. Cookies are part of
the HTTP header, so setcookie() must be called before
any output is sent to the browser. This is the same
limitation that header() has. You can use the output buffering functions to delay
the script output until you have decided whether or not to
set any cookies or send any headers.
Any cookies sent to you from the client will
automatically be turned into a PHP variable just like GET and
POST method data, depending on the
register_globals and
variables_order configuration variables. If you wish to
assign multiple values to a single cookie, just add [] to the
cookie name.
In PHP 4.1.0 and later, the
$_COOKIE auto-global array will always be set with any
cookies sent from the client.
$HTTP_COOKIE_VARS is also set in earlier versions of PHP
when the track_vars configuration
variable is set.
For more details, including notes on browser bugs, see
the
setcookie() function.