The associative arrays used to pass submitted form data to PHP
are $_GET for the GET method and $_POST for the POST method.
The register_globals setting
was the default in versions of PHP prior to 4.2.0. It was not a good
idea because it automatically assigned submitted form field data to
PHP variables, thus opening up a security hole for potential hackers,
who could attempt to break into PHP code by initializing variables to
values of their choice.
The difference between a text box and a text area is that although they both accept text for form input, a text box is a single line, whereas a text area can be multiple lines and includes word wrapping.
To offer three mutually exclusive choices in a web form, you should use radio buttons, because checkboxes allow multiple selections.
You can submit a group of selections from a web form using a
single field name by using an array name with square brackets, such as
choices[], instead of a regular
field name. Each value is then placed into the array, whose length
will be the number of elements submitted.
To submit a form field without the user seeing it, place it in a
hidden field using the parameter type="hidden".
You can encapsulate a form element and supporting text or
graphics, making the entire unit selectable with a mouse-click, by
using the <label> and
</label> tags.
To convert HTML into a format that can be displayed but will not
be interpreted as HTML by a browser, use the PHP htmlentities function.