Secure Sockets Layer (SSL) is a protocol for enabling data encryption on the Internet and for helping web site users confirm the owner of the web site. SSL is most commonly used to protect communications between web browsers and servers.
However, it is increasingly used for server to server communications and for web-based applications. SSL Certificates help you keep your customers’ transactions secure with strong encryption, and you’ll speed through enrollment with automated domain control validation.
They are also used so that the web browser / visitor / customer to your website knows that your site is secure and can trust that their details will be safe. This is especially important if you have a payment gateway, shopping cart or need to take credit card details for any online payments.