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\centerline

Syntax: \centerline{text}
This is the original TeX command for centering short text.

center environment

Syntax
\begin{center}
First line \\\
second line \\\
\end{center}

The center environment allows multiple rows to be centered.
In the center environment, if the "first line" is too long, it will automatically wrap, and the text of the wrap is still centered, so this is a very common way to do it.