### Theory:

A Computer is an electronic machine that is used to perform any task quickly and easily. Due to the widespread use of computers in every field, today's life in the world would be impossible without them.

Characteristics of Computer:
To understand why computers are such an unavoidable part of our day to day lives, let us discuss some of their characteristics,
• Speed − Generally, a computer can carry out three to four ($$3 -4$$) million instructions per second.
• Accuracy − Computers provides a very high degree of accuracy. Errors may occur only due to human mistakes such as inaccurate data, wrong instructions or bugs in chip.
• Reliability − Computers can do redundant works (same type) repeatedly without any errors due to tiredness or careless, which are so common among humans.
• Versatility - Computers can carry variety (wide range) of work from data entry, Online Tutoring and ticket booking to complex mathematical calculations and continuous astronomical observations. If you can provide the necessary data with correct instructions, the computer will do the processing.
• Storage Capacity − Computers can store a huge amount of data at a lesser cost compared to conventional storage of files (Paper). Also, data is safe from normal wear and tear associated with paper.
It is necessary to note that there are three key units in the computer. Understanding these units will make us to operate a computer with ease. In this chapter, let us learn,
• What are the units?
• What are the functions of each of these units?
Parts of Computer:
Computer system has three basic units that help the computer to perform operations, which are given below:
1. Input Unit
2. Central Processing Unit (CPU)
3. Output Unit

The functions of these units are discussed in the next section.
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