SSL stands for Secure Sockets Layer and is used is to keep sensitive information sent across the Internet encrypted so that only the intended recipient can understand it. This is important because as the information you send over the Internet is passed from PC to PC to get to the destination server. Any computer in between you and the server can see your credit card numbers, usernames and passwords, and other sensitive information if it is not encrypted with an SSL certificate. When an SSL certificate is used, the information becomes unreadable to everyone except for the server you are sending the information to. This protects it from hackers and identity thieves.
In addition to encryption, a proper SSL certificate also provides authentication. This means you can be sure that you are sending information to the right server and not to a criminal’s server. Why is this important? The nature of the Internet means that your customers will often be sending information through several computers. Any of these computers could pretend to be your website and trick your users into sending them personal information. It is only possible to avoid this by using a proper Public Key Infrastructure (PKI), and getting an SSL Certificate from a trusted SSL provider.