Forms make HTML documents truly interactive.
It is important to note that since CGI scripts reside on the server, security issues are a major concern. For example, many ISP provide CGI's that process form data from guestbook entries. For those who have no access to CGI's, mailto forms are an option, whereby the contents of the form are e-mailed to the author of the form, instead of being passed to the server. Mailto forms are unsecure, so do not use them to request sensitive information , i.e., visa numbers, personal address info, etc. This tutorial covers the basics of form tags and their attributes, and provides a few examples of on-line forms.