The document’s overall class is defined with the \documentclass command, which is normally the first command in a LaTeX source file.
\documentclass[options]class>
The following document class names are built into LaTeX. Many other document classes are available as separate packages (see Overview of LaTeX).
For a journal article, a presentation, and miscellaneous general use.
Full-length books, including chapters and possibly including front matter, such as a preface, and back matter, such as an appendix (see Front/back matter).
Mail, optionally including mailing labels (see Letters).
For documents of length between an article and a book , such as technical reports or theses, which may contain several chapters.
For slide presentations—rarely used nowadays. The beamer package is perhaps the most prevalent replacement (https://ctan.org/pkg/beamer). See beamer template, for a small template for a beamer document.
Standard options are described in the next section.