jPlayer is an open-source, cross-platform media player library written in JavaScript that allows developers to easily embed and control audio and video playback within web pages using HTML5 and Flash. It offers a wide range of options for customization and has extensive support for media formats and codecs.
YouTube is a video sharing website where users can upload, watch, and share videos. It uses a complex system of backend databases and servers to handle the massive amounts of data and user traffic.