All user input GET and POST can be retrieved with get, post and get_post function.
get
Retrieve the GET input
$id = get("id"); // get the parameter 'id'
post
Retrieve the POST input
$id = post("business_id"); // get the post parameter
get_post
Retrieve the GET + POST input
$id = get_post("name"); // get the parameter from get and post
cookie
Get the cookie
$id = cookie("login"); // get the cookie
Filter
The input functions can also filter the input, by passing a filter constant as second parameter:
$id = get("name", FILTER_SANITIZE_MAGIC_QUOTES );
Here is the list of the filter you can use:
http://www.php.net/manual/en/filter.filters.php