# What are the classes and packages that must exist in a simple Latex file [duplicate]

I am a new Latex user and I have this question: What are the classes and packages that must exist in a simple Latex file?

Books recommendation are so appreciated.

## marked as duplicate by Chris H, CarLaTeX, TeXnician, Andrew Swann, ZarkoAug 3 '17 at 10:09

• Incidentally, there can only be one \documentclass instruction per LaTeX document. Which document class you should use greatly depends on your typesetting needs -- about which, alas, you haven't told us anything so far. – Mico Aug 3 '17 at 8:56
• A simple file could even not load any document class: \def\normalsize{\normalfont} \begin{document} Hello, {\em baby} \end{document} From here it depends of what you need. – Fran Aug 3 '17 at 11:47