I have used many OS,such as windows，andriod ，linux and IOS.I think the most important OS to me is Windows.I have used the version of Win from 98 to 10. I think it is the most popular and most powerful OS in the world now.

It made by the Microsoft, and its graphical interfaces which learning from the IOS (made by the APPLE) is more useful and availble than IOS，so it became more popular than IOS in PC.

Now， in win 10，it has  more beautiful interface and useful fuction.