HTML forms are fundamental to web authentication, collecting user credentials and transmitting them to a web server for processing. To understand how forms work, one must grasp the basics of HTTP requests, including GET and POST methods, which determine how form data is transmitted to a web server. Understanding form security is crucial, as it involves using SSL to encrypt communication between the browser and website, preventing Cross-Site Request Forgery (CSRF) attacks by implementing CSRF tokens and cookies, and ensuring that sensitive information is not cached or logged on the server-side. By mastering these concepts, developers can build secure websites that protect user data and prevent malicious attacks.