SSL (Secure Sockets Layer) is a method of ensuring that information submitted through your Web site is secure and cannot be accessed by unauthorized users. When a site offers an SSL-secured form, the information submitted via that form (typically credit card information) is encrypted using a special certificate key and then decrypted with another key after it has been transmitted.
When users access a site secured with SSL using their browser, a symbol displays in their browser windows indicating that the site is secure.