check_markup($text, $format_id = NULL, $langcode = '', $filter_types_to_skip = array())
Runs all the enabled filters on a piece of text.
Note: Because filters can inject JavaScript or execute PHP code, security is vital here. When a user supplies a text format, you should validate it using $format->access() before accepting/using it. This is normally done in the validation stage of the Form API. You should for example never make a preview of content in a disallowed format.
Note: this functio