Customers in a store can see who they are dealing with and can be sure that if something is wrong with their purchase, they'll have recourse to the store manager or owner. However on the Internet, website visitors have no reliable way of knowing who owns the ecommerce site they are about to buy from. They are also exposed to all the security risks associated with sending data over an open network (the Internet).
When customers visit a website to make an online purchase, they want to know who they'll be paying and that the personal information they submit to the site cannot be intercepted. This is the purpose of an SSL digital certificate.
Use of SSL (Secure Socket Layer) and a digital certificate enable a web browser (your customer) to communicate securely with your website, assuring the customer of 3 things:
1. That the website really is who it claims to be.
2. That credit card numbers, etc are encrypted and cannot be intercepted.
3. That the data sent and received cannot be tampered with or forged.
Note: The "Premium SSL" just $99.95/yr. is recommended. This SSL offers your visitors high credibility as the issuing process includes domain verification and domain name control, identity of requesting person or company, and authority to make request.