Let us identify the major characteristics of a computer. These can be discussed under the headings of speed, accuracy, diligence, versatility and memory.
Speed: As you know computer can work very fast. It takes only few seconds for calculations that we take hours to complete. Suppose you are asked to calculate the average monthly income of one thousand persons in your neighborhood. For this you have to add income from all sources for all persons on a day-to-day basis and find out the average for each one of them. How long will it take for you to do this? May be one day, two days or one week? Do you know your small computer can finish this work in few seconds? The weather forecasts that you see every day on TV is the result of compilation and analysis of huge amount of data on temperature, humidity, pressure, etc. from various places processed by computers. It takes few minutes for the computer to process this huge amount of data and give the result. You will be surprised to know that computer can perform several million (1,000,000) of instructions and even more per second. Therefore, we determine the speed of computer in terms of microsecond (10-6 part of a second) or nano-second (10-9 part of a second). From this you can imagine how fast your computer can perform.
Accuracy: Suppose some one calculates faster but commits a lot of errors in computing. Such result is useless. There is another aspect. Suppose you want to divide 15 by 7. You may work out up to 2 decimal places and say the quotient is 2.14. I may calculate up to 4 decimal places and say that the result is 2.1428. Some one else may go up to 9 decimal places and say the result is 2.142857143. Hence, in addition to speed, the computer provides very high level of accuracy or correctness in computing.
Diligence: A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it is better than human being in routine type of work.
Versatility: It means the capacity to perform completely different type of work. You may use your computer to prepare payroll slips. Next moment you may use it for inventory management or to prepare electricity bills or prepare accounts, etc. Therefore computer is highly versatile.
Power of Remembering: Computer has the power of storing huge amount of information or data.Information can be stored and recalled as long as you require it, for any number of years. It depends entirely upon you, how much data you want to store in a computer and when to use or retrieve these data.
No IQ: Computer is a dumb machine and it cannot do any work without instructions from the user. It is considered as a faithful idiot that can only perform the instructions given to it at tremendous speed and with high accuracy without understanding of the work being done. Computer has to be guided as to what you want to do and in what sequence. So a computer cannot take its own decision as you can.
No Feeling: It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even after long hours of work. It does not distinguish between users.
Storage: The computer has an in-built memory where it can store a large amount of data. You can also store data in secondary storage devices such as floppies and CDs, which can be kept outside your computer and can be carried to other computers.