Binary, or the base 2 numeral system, is a system of noting down numbers only using 0 and 1 (unlike the 0 - 9 of our, decimal system). A digit which can only have the value of 0 or 1 is boolean.
Decimal: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9... 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, [...] 98, 99... 100, 101, 102, 103...
Binary: 0, 1... 10, 11... 100, 101, 110, 111... 1000
All home computers store their data in binary notation, as it is the simplest and cheapest method. A single unit of data that holds this value in a computer is a bit. An 8-bit computer, for example, deals with 8 digits of data (00000000 - 11111111), which can represent 256 different values - this is why such computers have this limit set on amount of the color palette and other things.
0 0 0 0 0 0 0 0
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amount:128 64 32 16 8 4 2 1
Example reading of binary number 101010:
1 0 1 0
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amount: 8 + 0 + 2 + 0 = 10
A system of encoding numbers in binary that incorporates negative numbers.
000 001 010 011 100 101 110 111 0 1 2 3 4 5 6 7 - unsigned 0 1 2 3 -4 -3 -2 -1 - two's complement