For fairly simple type of websites, average security system of web server on your web hosting account maybe enough to protect your websites. Simple informational http communication don’t need further protection against hacker attack. On the other hand, if you build an e-store, e-commerce, or web service which need secure transaction, you need something to protect your website against stealing information about you and your customers private details which may occur when web server communicate with client.
Secure Sockets Layer (SSL), are cryptographic protocols that provide security for communications over networks such as the Internet. It uses digital certificate issued by valid certification authority such as VeriSign, GeoTrust an WebTrust. For complete list of Certification Authority included in Mozilla as a leader in browser software, you can see here. SSL also need to ready to work in different environment such as Linux web hosting or Windows web hosting.
Another protocol for transmitting data securely over the World Wide Web is Secure HTTP (S-HTTP). Whereas SSL creates a secure connection between a client and a server, over which any amount of data can be sent securely, S-HTTP is designed to transmit individual messages securely. SSL and S-HTTP, therefore, can be seen as complementary rather than competing technologies. Both protocols have been approved by the Internet Engineering Task Force (IETF) as a standard.
Many other method to secure your website from the attacks. To discuss more about security of web hosting, including SSH and another trechnical problem, you can get more information by visiting forum of webhosting UK.