documentclass

\documentclass[option]{class}

eg.\documentclass[11pt,twoside,a4paper]{article}

 

 

 

 

Book:\part{}, \chapter{}, \section{}, \subsection{}, \subsubsection{}, \paragraph{}, \subparagraph{}.

Report:\part{}, \chapter{}, \section{}, \subsection{}, \subsubsection{}, \paragraph{}, \subparagraph{}.

Article:\part{}, \section{}, \subsection{}, \subsubsection{}, \paragraph{}, \subparagraph{}.