There are some OS I know:

computer: used(Windows、Linux、DOS)、 never used(Mac OS、UNIX)

Mobile phone: used(Android、Windows phone)、 never used(symbian、IOS、BlackBerry OS)

Windows is still the most popular operiting system in the world.It was created by Micsoft.Windows OS is very easy to use and has many powerful fuctionsso it is adopt many peoplesuch as Office workeror some person who even don't know about computer.But it also has many loopholeso it is very easy to be attack