HTTP (hypertext transport protocol) is the protocol used to serve web pages. Although HTTP (web) serving is a well known service of many hosts on the Internet, there is no restriction that says it cannot be provided to an intranet. Many organizations, such as banks, accounting firms and etc., offer certain HTTP-based services only via an intranet for better control over access and security.
HTTP, generally speaking, is an end-user oriented protocol. As such, the latency and efficiency of serving HTTP requests is somewhat forgiving. This makes HTTP a protocol that is suitable for the Internet because the available bandwidth between two hosts cannot be guaranteed.
For security purposes, HTTPS (HTTP via SSL, secure socket layer) permits end-to-end encryption. This makes communication secure, even though the traffic has to go through potentially many routers along the way.