The language we use to communicate with each other is comprised of words and characters. We understand numbers, characters and words. But this type of data is not suitable for computers. Computers only understand the numbers.

Computers represent data in sets of binary digits. The representation is composed of bits, which in turn are grouped into larger sets such as bytes.

A **bit **is a binary digit that represents one of two states. The concept of a bit can be understood as a value of either 1 or 0, on or off, yes or no, true or false, or encoded by a switch or toggle of some kind.

While a single bit, on its own, is able to represent only two values, a string of bits may be used to represent larger values.

A **byte **is a bit string containing the number of bits needed to represent a character. On most modern computers, this is an eight bit string.

The Number Systems used in computers are:

- Binary number system ( 0, 1)
- Octal number system ( 0 – 7 )
- Decimal number system ( 0 – 9 )
- Hexadecimal number system ( 0 – 9, A, B, C, D, E, F )

**Comparison of values in different bases**:

Decimal value | Binary value | Octal value | Hexadecimal value |
---|---|---|---|

0 | 000000 | 00 | 00 |

1 | 000001 | 01 | 01 |

2 | 000010 | 02 | 02 |

3 | 000011 | 03 | 03 |

4 | 000100 | 04 | 04 |

5 | 000101 | 05 | 05 |

6 | 000110 | 06 | 06 |

7 | 000111 | 07 | 07 |

8 | 001000 | 10 | 08 |

9 | 001001 | 11 | 09 |

10 | 001010 | 12 | 0A |

11 | 001011 | 13 | 0B |

12 | 001100 | 14 | 0C |

13 | 001101 | 15 | 0D |

14 | 001110 | 16 | 0E |

15 | 001111 | 17 | 0F |

A nibble, is a number composed of four bits. Being a half-byte, the nibble was named as a play on words.