Question

what is computer how is it a useful device

Answer 1

computer is an electronic machine. which is very usefull and can do many thinks in seconds and can have many things in it. and even can manage everything which a human body cannot do that!

Answer 2

computer is an electronic device in other words we can say computer -Common Operating Machine Particularly used for Technological Engineering Research.
it is useful to gain knowledge of anything if it is related with our subjects or not ,we can play many games and today we see the toppers of various fields their secret of success is only computers and today is the era of competition so keep learning and gaining knowledge with computer .