The simplest programs that do word processing are known as text editors. These programs are designed to be small, simple, and cheap. Almost every operating system made comes with at least one text editor built in. Each letter is assigned a numeric value that will fit in eight digits of binary notation.
Text editors can be wonderful programs.
The biggest advantage is the price. There is probably already one or more installed on your computer. You can find a number of text editors for free on the Internet. Text editors are also very easy to learn. Since they don't do a lot of fancy things, they are generally less intimidating than full fledged word processor packages with all kinds of features.