The Apache Httpd interface to OpenSSL
mod_ssl is a module for the Apache HTTPD webserver which allows it to perform SSL and TLS encryption on connections. Documentation is provided by Apache covering installation and setup for httpd 2.0 and 2.2
This tag should be used for questions around using mod_ssl in your application, extending it, controlling the state from your application, writing other Apache modules that talk to it and similar.
For questions around setting it up, and advanced configuration, the mod-ssl tag on ServerFault is likely to be a better place to ask.