Computers were originally built to do repetitive calculations with a high degree of reliability. Humans, you see, get bored and tired. Having a person do the same kind of arithmetic over and over again leads to fatigue and errors. The original solution was to have the same calculation performed by more than one person and then compare the answers. Correct answers tend to agree with each other, but mistakes are likely to be different. Mechanical calculators tend to either work or not, and it's pretty clear when they do not. Computers are the same way. Because of their origin, computers have one essential property to keep in mind: Computers can only manipulate numbers. Of course, humans have written millions of programs that hide this fact. Computers can recognize voices and speech commands, can identify faces, can play chess, and do millions of things that appear to be non-numerical. The software hides what is happening underneath. To get a computer to create a picture or music, we must devise some sort of code that allows pictures and music to be made into numbers. Truly, at the lowest levels of abstraction computers only handle numbers. People see computers using letters and words, for example, every day. A keyboard is fundamental to a computer, and almost all computers have them. Surely, computers can manipulate letters. No, not unless a method is devised to convert the symbols we see as letters and the keys we press into numbers. Then the computer can manipulate the numbers. This is an encoding, and computers use many of them. Characters are just one of the first that was devised, and so it shall be the first one discussed.