HTTP - hyper text transfer protocol, a way to transfer website data via Internet. At first, was created for transfer of HTML documents, now most of website data (audio, video, images etc.) is downloaded through this protocol. HTTP has several methods - to check a website, to get the data from the server, and to upload some information from client to the site. More about them you may find in this article. HTTP has its secure version - HTTPS
This protocol is used by clients to review web pages. Thus, to check a website, we should use it too. Website monitoring services, like HostTracker, perform HTTP checks to make sure that the site is operating well.