Digital Encoding is the process of transferring data from a format that a human can recognize into a format that a computer can use, as well as change it back again. The format that the computer can use is called binary, and only uses “0” or “1”. The format that a human can recognize can be anything, from the characters that you're reading in this text right now, to that picture you took while on vacation last year.
There are two types of encoding schemes that can be used. Either a variable length encoding scheme, which uses a variable number of “bits”, the slots that can hold a “0” or “1”. The upside of this format is that you can always add new pieces of information to be encoded by simply giving it a longer string of bits. The main disadvantage of this system is that it can be hard to tell where one group of bits, or “bitstring” ends.
The other type of encoding scheme is a fixed length encoding scheme. This means that each piece of information to be encoded will use the same number of bits. The nice thing about this format is that it is much easier to translate than variable length. The downside is that before you begin to design your fixed length system you have to know how many different pieces of information you will need to encode. For example, if you want to encode the English alphabet capital letters, then you need to be able to encode 26 different pieces of information.
Since each bit can only contain a “0” or “1”, there is a fairly easy way to determine how many possibilities you will have with a given length bitstring. The formula to figure this out is 2^n, where n is the number of bits in your string. So for a bitstring length of 4, the formula would read 2^4 and you would have 16 possible combinations. Obviously not enough to hold the English alphabet, but you could certainly hold the numbers 0-9.
