What does an operating system do$?$ Why do you need an operating system?

How do operating systems make a programmer$$s job easier? How do operating systems make life easier for end users?

What kinds of operating systems are used in the devices that you own? On your personal computer? Your mobile phone? The set$-$top box on top of your television? What other operating systems have you used or experienced? If you cannot tell which operating system is in each of these devices, see if you can search the internet to find out.

Which mobile OS has a larger global market share$$Android or iOS? Which has returned more money to developers through its app store? Is this data what you would expect? Why or why not?