The SSL (secure socket layer) protocol is the web standard for encrypting communications between users and web sites.
Data sent via an SSL connection is protected by encryption, a mechanism that prevents eavesdropping and tampering with any transmitted data.
SSL provides businesses and consumers with the confidence that private data sent to a web site, such as credit card numbers, are kept confidential.
If you are running e-commerce transaction or you have a web site that request for customers private & confidential information, it is strongly recommended that you installed SSL to your site.
In other words, to be a responsible web site owner, you shall have a SSL certificate in order to protect your customers info to be tapped or stolen via Internet.