ASCII vs UNICODE
Why and how do we use these character sets?
Why do we use character sets to represent text?
Well lets see, a computer can't just magically print letters on a screen it has to use binary. Binary? How does that work well it uses lots of transistors on the CPU which turn on or off these are represented as a 1 (on) or a 0 (off). So the computer has to send messages around the computer using binary and so big companies such as ASCII created character sets which use binary so that the computer can understand it.
For example ASCII has:
A=01000001
What is the difference between ASCII and UNICODE?
ASCII is what is called an 8 bit binary set this means there has to be eight 0's and 1's and that means there can only be 256 different characters. This is fine for us as there are only 26 letters in the alphabet, 10 digits and a couple of signs and punctuation. But for our Chinese friends and others who have thousands of characters this isn't fine as we leave them out.
So instead some bright chap came up with the idea of Unicode a character set with 16 bits that means there is about 65 thousand different characters we could use perfect for those languages with loads of characters and just fine for us.