### Producing a LaTeX Input File

The first line of the input file should normally consist of an appropriate \documentclass command. If an article (or similar document) is to be produced on A4 paper, and if the main body of the text is to be set with a font whose natural size is 12 point', then the appropriate \documentclass command is

\documentclass[a4paper,12pt]{article}

Other forms of the \documentclass command can be used for letters, reports or books. If 12pt is omitted from the \documentclass command (with the preceding comma), then the document will be set in a 10 point' size. One may also replace 12pt with 11pt.

The documentstyle command may be followed by certain other optional commands, such as the \pagestyle command. It is not necessary to find out about these commands when first learning to use LaTeX.

After the \documentclass command and these other optional commands, we place the command

\begin{document}


This command is then followed by the main body of the text, in the format prescribed by the rules of LaTeX.

Finally, we end the input file with a line containing the command

\end{document}