what is computer?

there are lots of explanations of computer as follows:

• a machine for performing calculations automatically
• calculator: an expert at calculation (or at operating calculating machines)
  
  
• A computer is a programmable machine that receives input, stores and manipulates data, and provides output in a useful format.
  
  
• Computer is an IEEE Computer Society practitioner-oriented magazine issued to all members of the society. It contains peer-reviewed articles, regular columns and interviews on current computing-related issues. ...
  
  
• Computer music is a term that was originally used within academia to describe a field of study relating to the applications of computing technology in music composition; particularly that stemming from the Western art music tradition. ...
  
  
• Before electronic computers became commercially available, the term "computer", in use from the mid 17th century, literally meant "one who computes": a person performing mathematical calculations. ...
  
  
• Computer Engineering (also called Electronic and Computer Engineering, Computer Science & Engineering, or Computer Systems Engineering) is a discipline that combines both Electronic Engineering and Computer Science. ...
  
  
• A programmable device that performs mathematical calculations and logical operations, especially one that can process, store and retrieve large amounts of data very quickly; A person employed to perform computations
  
  
• Computing is a weekly newspaper/magazine published by Incisive Media for IT managers and IT professionals in the United Kingdom. ...
  
  
• Computing (Urdu: کمپیوٹنگ), a monthly publication, the magazine is in Urdu Language. The first issue was published February 25, 2007. From the very first issue, Computing caught the attention of IT magazine-readers in Pakistan. ...
  
  
• Computing, subtitled Archives for Scientific Computing, is a scientific journal published by Springer publishing research in computer science and numerical computation. Its ISSN is 0010-485X for the print version and 1436-5057 for the electronic version. ...
  
  
• An electronic machine that receives, processes and presents data. A computer can be programmed to perform complicated tasks, like solving complex mathematical equations or controlling a flight simulator. ...
  
  
• Electronic machine capable of performing calculations and other manipulations of various types of data, under the control of a stored set of instructions. The machine itself is the hardware; the instructions are the program or software. ...
  
  
• This is the large, usually black or beige, box that sits on the floor under or near your desk. This unit will generally have some lights on it that indicate if it is turned on or not.
  
  
• A program that performs one of the tasks for which a computer is used, such as word processing or numerical computations.