Why does LaTeX show an error when using an underscore in text?

In LaTeX the underscore character is reserved for creating subscripts in math mode. If it is used directly in normal text, LaTeX produces an error. To display it properly you need to escape it using commands like \_ or \textunderscore.

How can I print an underscore in LaTeX?

You can print an underscore in LaTeX by using commands such as \_ or \textunderscore. These commands allow the symbol to appear in both math mode and text mode without causing compilation errors.

Can I use the underscore character in LaTeX math expressions?

Yes. In math mode the underscore is normally used to create subscripts, such as x_1 or \Lambda_0. If you want to display the underscore symbol itself, you should use commands like \_ or \textunderscore.

What is the purpose of the \verb command in LaTeX?

The \verb command prints text exactly as it appears in the source code without interpreting LaTeX commands. It is useful for displaying code, commands, or text containing characters like underscores.

Fix Underscore Symbol Error in LaTeX Documents

It is common to see an error in LaTeX when typing “_” in normal text. The reason is that the underscore symbol is reserved for subscripts in mathematical expressions.

Because of this, users often face issues when writing technical terms, file names, or variables such as m_n.

Table of Contents

Printing an Underscore in Math Mode
Using an Underscore in Text Mode
Another Way to Print an Underscore
Conclusion

Printing an Underscore in Math Mode

LaTeX provides a built-in command \textunderscore that prints the “_” character safely in normal text.

You can also display it by escaping the symbol using \_. Sometimes it is written as {\_} to keep the formatting stable inside text.

\textunderscore
\_

\documentclass{article}
\begin{document}
 \[ \_ Underscore \_ \]
 \[ One{\_} Two{\_} Three \]
 \[ \Lambda \textunderscore 0 \rightarrow \Lambda_0 \]
 \[ Underscore{\_} in \ math{\_} mode \]
\end{document}

Using an Underscore in Text Mode

The same commands can also be used in text mode. Both \textunderscore and {\_} allow you to print the “_” character safely inside normal text.

\documentclass{article}
\begin{document}
  \textunderscore Underscore\textunderscore\\[4pt]
  One{\_} Two{\_} Three\\[4pt]
  $\Lambda$\textunderscore 0 $\rightarrow$ $\Lambda_0$\\[4pt] 
  Underscore{\_} in\textunderscore text{\_} mode
\end{document}

Another Way to Print an Underscore

LaTeX also provides a default command called \verb|...|. This command prints characters or commands exactly as written, without compiling them.

You simply place the content between |...|. However, the output appears in a slightly different monospaced font style.

This command works in both text mode and math mode.

\documentclass{article}
\begin{document}
   \verb|_Underscore_|\\[4pt]
   \verb|One_Two_Three|\\[4pt]
   \verb|\Lambda_0| $\rightarrow$ $\Lambda_0$\\[4pt] 
   \verb|Underscore_in_text_mode|\\[4pt]
\end{document}