Apache is a free and open-source cross-platform web server software.
Java is a class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible.
Liferay is an open-source company that provides free documentation and paid professional service to users of its software.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.