The Term Computer comes from the word compute means to calculate. Therefore, "Computer is an calculating device that can perform arithmetic calculations at an enormous speed."
Computer is basically an information processing machine that processes the data to provide us information.
Now the question is, what is data and information??
Data : -  Data are the raw facts and figures that are gathered and entered into the computer as Inputs.
Information :- The processed form of data is called information. The data entered in the computer are processed to give the user, useful information which is also known as output.
So functioning of a computer can be shown as :-

 In other words, we can define computer as :-

"Computer is an electronic device, capable of processing arithmetic and logical instructions at a rapid rate and with greater accuracy i.e. capable of processing fast and accurate information."