An SSL Certificate lets visitors know that they are really doing business with you (not an impostor's "spoof " site) and that the information they send through your site-such as credit card numbers, online forms, and financial data-is protected from interception or alteration over the Web.
How it works:
1. - A customer contacts your site and accesses a secured URL: a page secured by a Server ID (indicated by a URL that begins with "https:" instead of just "http:" or by a message from the browser).
2. - Your server responds, automatically sending the customer your site's digital certificate, which authenticates your site.
3. - Your customer's Web browser generates a unique "session key" (like a code) to encrypt all communications with the site.
4. - The user's browser encrypts the session key with the your site's public key so only your site can read the session key. Depending on the browser, the user may see a key icon becoming whole or a padlock closing, indicating that the session is secure.
5. - A secure session is now established--all communications will be encrypted and can only be decrypted by the two parties in the session. It all takes only seconds and requires no action by the user. - Updated: December 24, 2002