LaTeX Error: Missing $ inserted
The "Missing $ inserted" error means you used a math-only character — such as _, ^, &, or a symbol like \alpha — in normal text. Fix it by wrapping the math in $...$, or escape the character if you meant it literally (e.g. \_ for an underscore).
Why it happens
Characters like _ (subscript), ^ (superscript), and math symbols only work inside math mode. Writing "H_2O" or "x^2" in plain text triggers the error.
Example
% Wrong:
The formula H_2O is water.
% Fix — math mode:
The formula $H_2O$ is water.
% Or escape a literal underscore in text:
The file is read\_me.txtFrequently asked questions
Why does an underscore cause this?
Underscore (_) is the subscript operator and only works in math mode. In text, write \_ for a literal underscore or wrap the expression in $...$.
I used \alpha and got this error
Greek letters and most math symbols are math-mode commands. Write $\alpha$ instead of \alpha in normal text.
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