> For the complete documentation index, see [llms.txt](https://overleaf-pro.ayaka.space/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://overleaf-pro.ayaka.space/latex/more-topics/09-commands-and-environments.md).

# Commands and environments

## Commands

LaTeX documents behaviour can be controlled by using specific command. Typical command structure is as following:

```
\commandname[optional argument]{main argument}
```

Note, that all commands **must** be proceeded by the backslash mark and the main argument must be included inside {..} pair.

Some commands have more than one arguments, for example:

```
\multicolumn{number of columns joined}{alignment}{content}
```

Some commands do not need {} pair to work well, for example:

```
\item Text being item content
```

Some commands have option arguments, for example:

```
\item[--] Text being item content
\\[2ex]
```

## Environments

A special type of command is the environment. Typical environment structure is as following:

```
\begin{environmentname}
 content
\end{environmentname}
```

For example:

```latex
\begin{center}
Sample text
\end{center}
```

or

```latex
\begin{enumerate}
\item First point
\item Second point
\end{enumerate}
```

Note, that all environments **must** start with \begin{environmentname} and finish with \end{environmentname}.

Some environments take arguments and optional arguments, like commands. For example

```latex
\begin{tabular}[table position]{column specifications}
 table content
\end{tabular}
```


---

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