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\documentclass{class} % Replace "class" with the class you're using. And no, that does not mean that it should become \documentIEEEtran{class}, you know what I mean
\begin{document}
\end{document}
Document Classes:
article - For articles in scientific journals, presentations, short reports, program documentation, invitations,
IEEEtran - For articles with the IEEE Transactions format
proc - A class for proceedings based on the article class
minimal - It is as small as it can get. It only sets a page size and a base font. It is mainly used for debugging purposes
report - For longer reports containing several chapters, small books, thesis,
book - For books
slides - For slides. The class uses big sans serif letters
memoir - For sensibly changing the output of the document. It is based on the book class, but you can create any kind of document with it [1]
letter - For writing letters
beamer - For writing presentations (see LaTeX/Presentations)
https://en.wikibooks.org/wiki/LaTeX/Document_Structure#Document_classes