**Representation of information**

**Binary Number System**

Computer understands binary numbers only. Binary number system use two symbols to represent data, i.e. 0 and 1 and base of binary number system is 2. In the table given below the decimal numbers are shown with their binary equivalents.

**DECIMAL BINARY**

0 0

1 1

2 10

Computer being a device easily understands two states i.e. ON (Current is coming for 1) or OFF

(No Current for 0). Thus all data and instruction given to a computer is expressed in these two states, known as binary states (Bi meaning two). In a computer, all work use the binary number system. As we measure distance in Kilometer, time in minutes or seconds, similarly we measure the amount of data in various terms as Memory Size (Bit, Byte, KB, MB)

**BIT **

It is the basic unit of information. It means BInary digit (BIT). It represents either a zero (0) or One (1). Computer works on the principle of “on” or “off” of electronic pulses. 1 represents the passing of the pulse while 0 means blocking of pulse. Bit is therefore the smallest unit of information. For example

0 1 bit

11 2 bit

110 3 bit

**BYTE**

It is a collection of 8 bits.

KILOBYTE (KB), MEGABYTE (MB) and GIGABYTE (GB)

They are collections of data and are illustrated in the table

They are collections of data and are illustrated in the table

Unit | Equals |

1 Bit | 0 or 1 |

1 Byte | 8 bits |

1 KB | 1024 bytes |

1 MB | 1024 KB |

1 GB | 1024 MB |

**ASCII**

When text is stored in a computer, every letter or other character is first converted to a code using only zeros and ones. Computer stores numbers, letters and other special character in a coded form. The most widely used coding system is the American standard code for information technology (ASCII) which can represent 256 different human understandable symbols by using 8 bit collection for each character.

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