microbrowser - AKA minibrowser or mobile browser

A microbrowser is a web browser for use on a handheld device such as a PDA or mobile phone. Microbrowsers are optimised to display Internet content effectively for small screens on portable devices and have small file sizes to accommodate low memory and bandwidth of wireless handheld devices. Typically they were stripped-down web browsers, but as of 2006 some microbrowsers can handle latest technologies like CSS 2.1 and Ajax.

A web browser is a software application that enables a user to display and interact with text, images, and other information typically located on a web page at a website on the World Wide Web or a local area network.

Underlying technology
A microbrowser sets up the cellular networks itself and gets content written in XHTML Mobile Profile (WAP 2.0), or WML (WAP 1.3 based on HDML). WML and HDML are formats suitable for transmission across limited bandwidth, and wireless data connection called WAP.

WAP 2.0 specifies XHTML Mobile Profile plus WAP CSS, subsets of the W3C's standard XHTML and CSS with minor mobile extensions.

New microbrowsers are full featured Web browsers capable of HTML, WML, i-mode HTML, cHTML, CSS, ECMAScript, and plug-ins such as Macromedia Flash.

The Handheld Device Markup Language (HDML) is a markup language intended to display on handheld computers, information appliances, smartphones, etc.. It is similar to HTML, but for wireless and handheld devices like PDA, mobile phones and so on. It has been replaced by WML.
Pioneers
The so-called microbrowser technologies such as WAP, NTTDocomo's i-mode platform and Openwave's HDML platform have fuelled the first wave of interest in wireless data services.

Wireless Application Protocol or WAP is an open international standard for applications that use wireless communication. Its principal application is to enable access to the Internet from a mobile phone or PDA.

Wireless Markup Language, based on XML, is a content format for devices that implement the WAP Wireless Application Protocol specification, such as mobile phones, and preceded the use of other markup languages now used with WAP, such as XHTML and even standard HTML

STNC Ltd., developed a microbrowser (HitchHiker) intended to present the entire device UI in 97. The demonstration a single core platform, running the GSM stack on the same processor as the application stack for this microbrowser (Webwalker) had 1 MIPS total processing power. In 99 STNC was acquired by Microsoft and HitchHiker became Microsoft Mobile Explorer 2.0, not related to the primitive Microsoft Mobile Explorer 1.0. HitchHiker is believed to be the first microbrowser with a unified rendering model, handling HTML and WAP along with EcmaScript, WMLScript, POP3 and IMAP mail in a single client.

A freeware browser for the PalmOS was Palmscape, written in 1998 by Kazuho Oku in Japan, who went on to found Ilinx. Still in limited use as late as 2003.

Popular microbrowsers
The following are some of the more popular microbrowsers. Some microbrowsers are miniaturized Web browsers,
NetFront by ACCESS Co., Ltd.
Nokia Series 40 Browser by Nokia.
Nokia web browser by Nokia.
Novarra nWeb.
Web Browser for S60 by Nokia.
Obigo Browser by Obigo AB (Sweden), 100% owned by Teleca AB
Openwave (Redwood, CA)
Opera Mobile by Opera Software ASA (Norway). - Capable of reading HTML and reformat for small screens
Pocket Internet Explorer by Microsoft Inc.
Wapaka Browser Java micro-browser by Digital Airways.
Picsel Browser by Picsel Techologies (Scotland).
Blazer by Palm.
PlayStation Portable web browser by Sony
Embider by Infraware

User-installable microbrowsers
Opera (browser) by Opera Software - supports all modern web standards supported by desktop browsers, including XHTML, CSS2 and Ajax. Has advanced Small Screen Rendering that adapts regular pages to small screen.
Opera Mini by Opera Software - supports most features of stand-alone Opera, but can run on less capable phones by offloading memory-intensive rendering to proxy server.
WinWAP by Winwap Technologies
Bluelark Bluelark bought by Handspring Inc.
Doris by Anygraaf Oy (Vantaa, Finland)
JOCA by InteracT!V, another proxy-rendering free software
NicheView by Interniche Technologies Inc.
Minimo by Mozilla Foundation.
MobileLeap
Palm™ Web Browser Pro by PalmOne, Inc. (Milpitas, CA)
Pixo by Sun Microsystems ( acquired by Sun July 2003)
RocketBrowser Rocket Mobile, Inc. (Silicon Valley, CA).
PocketWeb by tlogic.de (Heidelberg, Germany)
SAS
Skweezer by Greenlight Wireless Corporation
Thunderhawk by Bitstream Inc. (Cambridge, MA)
Wapaka
Webby Mobile by AnOriginalIdea
WebViewer by Reqwireless
Novarra nWeb
Wapaka by Digital Airways