The Wireless Application Protocol is a suite of communications protocols that allows mobile devices to connect to the Internet over global cellular networks. Before WAP, phone users didn't have the option to send and receive emails, browse the Web or download media content to their devices. WAP has largely died out in the United States and Europe because the technology has been replaced by high-speed 4G systems.
The initiative to create a universal Wireless Application Protocol began in summer 1997, leading to the formation of the WAP Forum. This group was tasked with creating a protocol that would govern all transactions of Internet content over digital cellular networks. The protocol had to work with different cellular network technologies and offer scalability to accommodate new networks and wireless devices. WAP 1.0 appeared a year later in April 1998 and allowed for the interoperability of different cellular equipment across different cellular networks.
When a user with a WAP 1.0-enabled phone attempts to access an Internet page from his phone, a transmission is sent to a mobile telephone transmission tower. The tower then relays the signal using a land-based line to an Internet-connected server containing a WAP gateway. The gateway acquires the page and converts it from HTML into Wireless Markup Language, or WML -- a language optimized for small, text-only displays. The document is then sent back to the tower and to the user's phone.
WAP 2.0 appeared in August 2001 as a means to bring WAP closer to modern Internet standards. It added support for Internet protocols such as IP, TCP and HTTP, as well as faster networks like GPRS and 3G cellular and modern digital devices such as pagers, PDAs and smartphones. It took into consideration the fact that modern cellular devices have smaller screens and that many of them offer touchscreen functionality. Plus, it expanded support for flexible user interfaces, meaning manufacturers could create customized user interfaces to differentiate themselves from competitors.
The most notable difference between WAP and WAP2 is that WAP 2.0 doesn't rely on a gateway, meaning a user's mobile phone can communicate directly with the Web server. This enables end-to-end HTTP, which is why cellular devices can stream audio and video files. Plus, although WAP2 supports WML, it typically relies on an upgraded language known as Extensible Hyper Text Markup Language - Mobile Profile, or XHTML-MP. The advantage to XHTML-MP is that it supports Cascading Style Sheets, meaning developers can more accurately customize layout and style.