Proxy with SSL support
SSL (Secure Sockets Layer) is cryptographic protocol which provide secure communications on the Internet.
HTTP proxies are especially usefull when it is possible to access not just general HTTP servers but also a secure HTTPS servers through it. Using SSL proxy you can safely shop online, visit secured forums, etc. still keeping your anonymity and privacy.
If in the address line before a server name there is the https:// prefix and if you could see the page through a proxy server, it means your proxy supports the SSL.
Except for pure protection, the SSL allows to organize 'a virtual tunnel' through a chain of proxy servers.