Wireless Application Protocol (WAP) is a technical standard for accessing information over a mobile wireless network. A WAP browser is a web browser for mobile devices such as mobile phones that uses this protocol. Various Internet protocols and technical properties are summarized under this term which adapt web content for small mobile phone displays, taking into account slower mobile internet connections. Today WAP is usually used for MMS (Multimedia Messaging Service). Most smartphones can read HTML and connect via UMTS (Universal Mobile Telecommunications System) or LTE (Long Term Evolution) to the Internet.
When mobile technology was gradually established in the 1990s, mobile phone calls and the new SMS (Small Message Service) were the focus of attention. But the fact that mobile devices could send and receive other information besides digital voice data and text messages soon became an important part of the modern lifestyle. WAP technology evolved analogously to the expansion of the Internet.
Two tasks needed to be solved with mobile Internet at that time. First, mobile data transmission capacity in the GSM network was limited and second, web content had to be played back on mobile phones with small mostly monochrome displays and small memory. Consequently, WAP solved this problem by reducing the amount of data transmitted and at the same time retaining an open and readable markup language. WAP came forth from the efforts of the WAP Forum, which is currently known as the Open Mobile Alliance (OMA). WAP was introduced in 1997.
The developers had to solve a dilemma which was that a readable markup language was data-intensive, while compact digital encoding was unreadable and closed. The solution was the WML (Wireless Markup Language), an open language that is compiled and transmitted to the WAP client. A proxy server known as a WAP gateway, is connected between the WAP client and web server and translates in two directions. The digital requests of the WAP client are converted to plain text, such as HTML, and sent to the web server, while the WAP gateway compiles the server responses and transmits them to the client. WMLC (Wireless Markup Language Compiled) is used for this purpose. Thus, WAP client and WAP gateway operate similarly to a conventional web browser.
The transfer of data is carried out within the GSM standard via GPRS or UMTS. Another possibility is the use of HSDPA (High Speed Downlink Packet Access).
WAP 1.x: In this version, users could use websites specifically optimized for WAP. Due to its requirements, the presentation of websites was characterized by minimalistic design and missing colors.
WAP 2.0: The further development of the WAP standard was not compatible with the previous version. Web content could be reproduced in more detail. Additionally, WAP 2.0 used a simple version of XHTML. CSS elements specially developed for WAP could be integrated. A gateway was no longer required for data transmission. Moreover, WAP 2.0 supported the HTTP web history.
The following functions can be used with WAP:
Mobile surfing on special WAP-optimized websites Ordering and paying for ring tones or mobile games Retrieving information services Pay services Sending and receiving of MMS Receipt of push messages Hazards WAP services were repeatedly discredited because what at first glance seemed to be a practical solution to pay for web services (WAP billing), provided scammers opportunities to cheat customers. When accessing a WAP website, the phone transmitted a unique number to the provider. With that number, the provider can in turn, contact the mobile service provider and get the mobile phone number of the user. Using the phone number, the fraudulent provider could then get paid for services by adding them to the monthly phone bill.
Today WAP plays only a marginal role for mobile Internet since for the most part, smartphones are used.  With such devices and a data plan, users can easily access mobile websites via UMTS or GPRS, which differ very little in terms of functionality and design from desktop versions. Even sites which were not optimized for mobile devices can now be used with a mobile web browser.