RISC OS is an Open Source operating system originally designed in Cambridge, England by Acorn Computers Limited. First released in 1987, its origins can be traced back to the original team that developed the Arm microprocessor. RISC OS is now owned by RISC OS Developments Ltd.
RISC OS Open Limited (ROOL) manages the source code to RISC OS, and is a good place to start if you want to find out about RISC OS. You can also find out more info at sites such as RISC OS Blog, riscos.info, The Icon Bar and RISCOSitory.
I hope to use this section of my site to host my code and applications that I have created over my many years of using RISC OS.