## TeX

TeX was the first language to get its own StackExchange site.

(Note that we will show examples in plain TeX mostly; if any example is to be compiled using LaTeX, it will be clearly stated.)

## 5 `X\bye`

A minimal document that compiles producing an output; we get a page with a 10-point "X" at the top and a centred page number "1" at the bottom. _... "X," said Tom, and added, leaving: "Bye!"_

## 4 `\bye`

When you say "bye" to TeX, it finishes the document; namely it closes the current paragraph if any is open, ships out the last page, and ends. Without this command, no document can be successfully produced.

## 3 `$a$`

Prints the mathematical symbol "a", that can stand for instance for a variable, function or a constant. Without the dollars, it would be the text symbol "a"; it is necessary to distinguish these two!

## 2 `<endline><endline>`

Two consecutive ends of line finish a paragraph. (One end of line behaves like a space.)

## 1 `%`

The percent sign starts a comment; the comment runs until the end of line, and eats the end of line together with leading whitespace on the next line.