In modern technology most information is stored and transferred in binary form. This means that the information is coded by a group of 0s and 1s (alternatively other symbols can represent the 0 or one). In A level Physics it is a key point to understand this storage.
Usually information is grouped in 8 binary digits, bits, these 8 bits are called 1 byte. To explain how this works an example is necessary.
To code 20 in 1 byte, the byte would read 0010100, the right most digit represents 2^0 the next along represents 2^1 and so on. Therefore this binary digit 0010100 is 2^2+2^4 (^means to the power of) which adds to 20. With a bit of practice you should be able to remember this easily.
This principle does follow from the logarithms in the earlier topic, each next digit gives increases the number of combinations (alternatives) in the same way as a logarithmic scale. One byte has 256 2^8 alternatives.
There are also other forms of encoding, mainly octal and hexadecimal octal of base 8 and hexadecimal of base 16, now these follow a very similar method of coding as the binary shown about. But the numbers of symbols are different, that is for octal there are 8 symbols from 0-7 and in hexadecimal there are 16. So for the coding 3A in hexadecimal (A stands for 10 B for 11 and so on till 15) the answer in our decimal system of our language would be 3*16^1+10*16^0. In the same way as before we multiply the symbol by the base to the power of the position the base is away from the left hand side.