A Secure Socket Layer (SSL) encrypts confidential data such as credit card numbers, passwords and other sensitive information.
SSL is a system designed to enable applications to transmit information back and forth securely and privately. When that secured connection is made, your customer sees a little lock icon at the bottom of the browser and https:// in front of your domain name instead of the usual http:// Without those little tell-tale marks, a customer may not trust that your site is a safe place to divulge private information and credit card details, and a potential sale could be stopped dead in its tracks.
128 Bit versus 40 bit encryption: In terms of what the numbers represent, "128" and "40" bit encryption refer to the size of the key used to encrypt the message. 128-bit encryption provides a significantly greater amount of cryptographic protection than 40-bit encryption. Most browsers, until recently, came with only 40 bit encryption. So, purchasing a 128 bit SSL certificate ensures your users that your site has the security necessary to protect their confidential information.
The Certification Authority is the company that sells you the SSL and certifies or warranties that your SSL will work. Examples of well known Certification Authorities are Verisign, Geotrust and Thawte.
Browser Compatibility is the percentage of browsers that will "recognize" your SSL certificate. All browsers created since 1995 should recognize any 128-bit SSL certified by a well known vendor.
And, what is a "warranty?" Verisign's description of their warranty: "NetSure protects you against economic loss resulting from the theft, corruption, impersonation, or loss of use of your VeriSign SSL certificate." So, in a way, it's like insurance. If you already have protection through your Merchant Account provider... you really don't need the extra insurance, but it might make you and/or your customers feel more secure.
So, why all the price differences? The major differences in prices reflect the level of browser compatibility plus "name brand" recognition that each certificate offers. For example, Verisign's "Secure Site" certificate is $349/year and promises 99% browser recognition as well as the #1 world-wide recognized "name brand" status. Kestrel Hosting's Discount Certificates, on the other hand, are purchased from a GeoTrust subsidiary company. This certficate is only $69/year and offers the same 128-bit encryption and 99% browser recognition as the more expensive versions, but the Site Seal is not familiar. So you can buy your jeans at Sears or Neiman Marcus... it just depends on how important name brand recognition is to you and your site!
* Free installation guaranteed for Kestrel Hosting clients only.
Some host providers charge an additional fee to enable SSL certificates on their servers.