You can type on the computer if you have work to do instead of using paper which saves trees.
Saving work documents on the computer is useful if you don't want to lose it on paper.
It can also help you with education because you can research on the computer through the internet to find facts, topics, and articles instead of getting books.
You can email, voice chat, and video chat on the computer instead of mailing letters to someone which costs money or going to someones house which takes time.
Computers changed the way of entertainment by streaming instead of going to the video store and renting or buying one because you can access every song and movie right a way when it comes out.