Apache is a free and open-source cross-platform web server software.
Pure CSS is a set of small, responsive CSS modules that can be used in web projects.
Progressive Web Apps (PWAs) are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.