Symbian evolved from Psion's EPOC in 1998. Symbian OS is currently owned by BenQ, Ericsson, Panasonic, Nokia, Siemens AG and Sony Ericsson.
There are several variations of the Symbian OS that are tailored for different devices. The capabilities of the Symbian OS depend on the device for which it was tailored. Each variation is called a Device Family Reference Design (DFRD).