Apache is a free and open-source cross-platform web server software.
Open Graph is a protocol that is used to integrate any web page into the social graph.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
Varnish is a reverse caching proxy.
W3.CSS is a CSS framework developed by the World Wide Web Consortium (W3C), the main international standards organisation for the World Wide Web.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.