Techopedia explains
Wireless Application Protocol (WAP)
The WAP cascading style sheet (CSS) is a mobile rendering of the World Wide Web that allows developers to format screen sizes for mobile device adaptability. Reformatting is not required when using WAP CSS content, which controls page layout compatibility with a variety of mobile device display screens.
The core interface of WAP architecture is the WAP datagram protocol, which manages the transmission layer protocols of Internet models and facilitates operations between mobile wireless networks and platforms, independent of upper layer protocols. The transport layer deals with physical network issues, allowing wireless global operations to readily access wireless gateways. A WAP gateway is a server that facilitates wireless network access.
The WAP Forum, now known as the Open Mobile Alliance (OMA), provides WAP tool testing, specification development and support for all mobile services.