Apache is a free and open-source cross-platform web server software.
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.
Unix is a family of multitasking, multiuser computer operating systems.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.