Hypertext Transfer Protocol defines how clients and servers exchange requests and responses for resources. Streaming systems can use it to request playlists, segments, images and account-related data. HTTP describes the exchange; it does not by itself determine a video's codec, picture quality, catalogue or the permissions attached to an account.
A practical example
A television app may first request a playlist and then make further HTTP requests for guide data and media segments. One request can fail while others succeed, so a visible menu does not prove that every media request is working.
A common misunderstanding
A successful connection to a website does not establish that a separate stream URL is reachable or authorized. The resources can use different hosts, paths, ports and access requirements.
Related terms
Stable technical definition. Editorial approach