What is it?
According to figures from industry analyst Canalys, the Symbian operating system had 65% of the "converged device" market - smartphones and wireless handhelds - in 2007. This still isn't an enormous market. According to the Symbian company's own figures, 200 million Symbian-equipped devices have been sold over the years.
If another of the company's figures is correct, users of these devices are among the most pampered in the world: there are supposed to be four million developers working on applications for the Symbian platform, one for every 50 customers, with 10,000 mobile applications available.
Nokia is in the process of acquiring all the shares in Symbian Ltd it doesn't already own. In June, with other leading mobile telecoms manufacturers from around the world, Nokia announced the Symbian Foundation. This will unite the various Symbian software platforms, including Nokia's S60, UIQ from Sony Ericsson, Motorola and others, and NTT Docomo's Mobile Oriented Applications Platform MOAP in a single, "open" mobile software platform.
The Foundation will offer a royalty-free Symbian licence, and has borrowed other approaches from the open source world. Some components are already available as open source products, and the intention is to provide "the most complete mobile software offering available in open source" within two years.
But in the meantime, acquiring Symbian skills and developing Symbian applications is an expensive business. Those skills are, however, well rewarded.
Where did it originate?
Symbian originated with Psion's EPOC operating system in the 1980s. The Symbian platform is now 10 years old: Symbian Ltd was formed as a partnership between Psion, Ericsson, Nokia and Motorola in 1998. The newly formed Symbian Foundation's board members include AT&T, LG Electronics, Motorola, Nokia, NTT DOCOMO, Samsung Electronics, Sony Ericsson, STM, Texas Instruments and Vodafone.
What is it for?
The Symbian OS is optimised to provide real-time services from limited resources. Symbian Software Developer Kits (SDKs) are available for C++ - the dominant language on the platform - and Java other languages such as Python are also used. Development takes the Model-View-Controller approach.
Best known and most widely used of toolsets is Nokia's Carbide.c++, based on the Eclipse initiative, of which Nokia is a member along with founder IBM.
There are different SDKs for the different user interface platforms, which, as well as look and feel, have their own sets of system applications for messaging, browsing, telephony and contact and calendar management.
How difficult is it to master?
Even experienced C++ developers will take time to adjust to some of the quirks of programming for the Symbian OS. Carbide.c++ is structured to guide developers though the steps required to write and deploy Symbian applications. Symbian also publishes downloadable reference applications and utilities written by its own engineers in C++ or Java, with full source code.
Where is it used?
The five leading handset manufacturers and biggest mobile networks worldwide all support Symbian.
What systems does it run on?
Most Symbian development is actually done under Microsoft Windows: when you download the SDK, you get documentation, and software which emulates Symbian on the PC. There are also plug-ins for Visual Studio, and Sun's Java Wireless Toolkit for Java Micro Edition.
Rates of pay
Junior C++ Symbian developers from £30,000 senior developers £40,000-£55,000.