The binary number system is a way of writing numbers with only 1s and 0s.
Everything on a computer (text, images, apps, etc.) is stored in binary.
Computers use 1s and 0s to represent ON and OFF:
1 means the electricity is flowing (ON)
0 means the electricity isn't flowing (OFF)
A single binary digit (either a 1 or a 0) is called a bit.
A group of four bits is called a nibble, and a group of eight bits (or two nibbles) is called a byte.
Just like 1000 metres is a kilometre, 1000 bytes is a kilobyte.
Table 1 shows the more common prefixes used when describing memory usage.
Table 1
| Unit | Number of bytes |
|---|---|
| Kilobyte (kB) |
103 = 1,000 bytes
|
| Megabyte (MB) |
106 = 1,000,000 bytes
|
| Gigabyte (GB) |
109 = 1,000,000,000 bytes
|
| Terabyte (TB) |
1012 = 1,000,000,000,000 bytes
|
Table 2 shows the less common prefixes used when describing memory usage.
Table 2
| Unit | Number of bytes |
|---|---|
| Kibibyte (KiB) |
210 = 1,024 bytes
|
| Mebibyte (MiB) |
220 = 1,048,576 bytes
|
| Gibibyte (GiB) |
230 = 1,073,741,824 bytes
|
| Tebibyte (TiB) |
240 = 1,099,511,627,776 bytes
|
If each bit can take 2 possible values (1 or 0), how many possible values can a nibble take?
Each bit in the nibble can take 2 possible values, so the nibble can take
24 = 2 × 2 × 2 × 2 = 16 possible values.