The Apache Project is an effort to develop and maintain an open-source HTTP server for modern operating systems including UNIX and Windows. The goal of this project is to provide a secure, efficient and extensible server that provides HTTP services in sync with the current HTTP standards.
PHP: Hypertext Preprocessor is a server-side scripting language designed for Web development, but also used as a general-purpose programming language. PHP code may be embedded into HTML code, or it can be used in combination with various web template systems, web content management systems, and web frameworks.
Google Calendar is an get a button on its browser toolbar that they can easily click to see upcoming events from google calendar, without ever leaving their page. And if they are on sites that have special events encoded, it can click the button to instantly add events to they calendar.