SSL is a standard for data security, it is most often used on the web in order to encrypt credit card transactions - you may know it as the little padlock that appears in the corner of your browser when you buy something online. SSL is used both to encrypt the data as it travels between the customer's computer and our web server, and to identify our web server as being the correct web server and not a hacker trying to intercept the details. In order to provide this protection, you need to purchase an SSL certificate - Digital Crocus manage this process for you and you don't need to get involved with the nitty gritty details of generating signing requests and web server installation.
There are two types of SSL certificate available, a normal certificate works for one subdomain - for example you might choose to get an SSL certificate for https://secure.yourdomain.com/ you would then be restricted to hosting all your secure content in one place. You have the option of choosing either https://yourdomain.com/ or https://www.yourdomain.com/ for your secure site but one certificate will not cover both. You can of course buy more than one certificate.
The other option is a wildcard certificate which covers https://.yourdomain.com/ and this would allow you to host an unlimited number of separate secure sites under your domain.
