A protocol is a standard for communication between computers. Most protocols are referred to by their abbreviations. For example, SMTP is an abbreviation for Simple Mail Transfer Protocol.

In URLs, the protocol used by the web server appears in lowercase before a colon. In text, protocol abbreviations typically appear in uppercase. Typical web protocols are HTTP, FTP, news, and so on.

Use title capitalization for the spelled-out form of protocol names (except in URLs) unless you know the name is handled differently. When in doubt, check the Microsoft Manual of Style index, or consult your project style sheet.

Microsoft style

http://www.microsoft.com

Internet Explorer supports Hypertext Transfer Protocol (HTTP).