Apache is a free and open-source cross-platform web server software.
cdnjs is a free distributed JS library delivery service.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Plesk is a web hosting and server data centre automation software with a control panel developed for Linux and Windows-based retail hosting service providers.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.