Wireless Application Protocol
At least part of this is a sort of down-trimmed HTML for the display of websites on the display of mobile phones and similar devices.
http://www.wapforum.org/
WAP is political, and therefore constantly on the verge of collapse, in a way distinct from HTTP, SMTP, HTML, and so on. In blunt language, WAP is tied more closely to telecommunications companies' "business models" than to customers' needs or engineers' vision. At least, that's a criticism made of it by apparently neutral observers.
LES: Until a couple of years ago (at least here in Brazil), WAP connection used to be charged by the minute like an ordinary call. Now, all mobile phone carriers I know of charge Internet connection by the kilobyte, and modern Web-enabled telephones support XHTML and even some Javascript. If that doesn't spell "WAP is dead", I don't know what does.