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A remark in LaTeX is a theorem-like environment for side comments, notes and observations that are not theorems. You get it from the amsthm package: load the package, set \theoremstyle{remark}, then define the environment with \newtheorem*{remark}{Remark} and write \begin{remark} ... \end{remark}. This guide is for researchers writing mathematical or technical papers who want remarks that look right and number the way their journal expects.
What a remark is used for in research writing
In a paper, a remark carries commentary that supports a result without being part of its logical chain: a note about a special case, a comparison with earlier work, or a caution. LaTeX has no built-in remark; you declare it as a theorem-like environment. The amsthm manual groups remark-type structures (Remark, Note, Notation, Claim, Summary, Acknowledgment, Case, Conclusion) under the remark theorem style, separate from the plain style (Theorem, Lemma, Corollary, Proposition, Conjecture, Criterion, Assertion) and the definition style (Definition, Condition, Problem, Example, Exercise, Algorithm, Question, Axiom, Property, Assumption, Hypothesis). For how remarks sit alongside theorems and proofs in a paper, see mathematics paper writing conventions: theorem and proof structure.
Install or access (official source only)
amsthm is the American Mathematical Society’s theorem package, distributed on CTAN with its manual (Using the amsthm package). The AMS document classes already include it, so with those classes you do not load it again. In any other class, add it to the preamble:
\usepackage{amsthm}Overleaf documents the same commands on its Theorems and proofs page, and you can compile there without a local installation.
How to write a remark in LaTeX, step by step
- Load the package in the preamble:
\usepackage{amsthm}. - Choose the style before defining the environment. Put
\theoremstyle{remark}first. The manual says that if no\theoremstyleis given the style is plain, and that you divide your\newtheoremcommands into groups, each prefaced by the appropriate\theoremstyle. - Define the environment. The first argument is the environment name, the second is the word printed in the heading.
- Use it in the body with
\begin{remark} ... \end{remark}.
\documentclass{article}
\usepackage{amsthm}
\theoremstyle{remark}
\newtheorem*{remark}{Remark}
\begin{document}
\begin{remark}
This observation is not needed for the main result.
\end{remark}
\end{document}The Overleaf page uses the same pattern: \theoremstyle{remark} followed by \newtheorem*{remark}{Remark}.
Adding a note to the heading
The manual describes an optional argument for adding information to a theorem heading, for example a source. In its lemma example, \begin{lem}[Alinhac-Lerner \cite{a-l}] prints as Lemma 2. (Alinhac-Lerner [4]). The same optional argument works on a remark: \begin{remark}[Special case] prints the text in parentheses after the word Remark.
Numbered, unnumbered and shared-counter remarks
The star in \newtheorem* makes an unnumbered environment; a starred environment cannot be numbered. Drop the star for numbered remarks. This table collects the variants the Overleaf page and the amsthm manual document.
| Goal | Declaration | Result as documented |
|---|---|---|
| Unnumbered remark | \newtheorem*{remark}{Remark} |
Heading without a number |
| Remark with its own counter | \newtheorem{remark}{Remark} |
Remarks numbered on their own sequence |
| Remark numbered within sections | \newtheorem{remark}{Remark}[section] |
Counter restarts in each section (the manual: with [section] the counter is reset) |
| Remark sharing the theorem counter | \newtheorem{remark}[theorem]{Remark} |
One sequence across theorems, lemmas and remarks (the manual’s [thm] option, as with its lemma example) |
| Number before the word | \swapnumbers placed before the \newtheorem list |
Headings read like 1.4 Remark instead of Remark 1.4 |
Overleaf’s shared-counter example uses \newtheorem{lemma}[theorem]{Lemma}, and the manual’s swap example places \swapnumbers before the plain and remark groups.
Output and how to read it
The Overleaf page describes the three styles by appearance: plain has a bold title and italic body; definition has a bold title and roman body; remark has an italic title and roman body. That is why a remark looks lighter than a theorem: it is set so it reads as commentary. If you need a different look, the manual covers custom styles through \newtheoremstyle.
Troubleshooting
My remark is bold or its body is italic
The environment was defined while the plain style was active. Because plain is the default when no \theoremstyle is given, a \newtheorem that comes before \theoremstyle{remark} uses plain. Move \theoremstyle{remark} above the remark definition.
Remark numbers do not appear
Check for the star: \newtheorem* cannot number. Remove it, and use the table above to pick the counter.
The proof ends without a square
That is a proof-environment question, not a remark one. See the end-of-proof symbol in LaTeX.
Variants and alternatives
amsthm is free and is the package both the Overleaf page and the AMS manual document, so this guide does not recommend a second package. Instead of switching packages, change the look of a remark with \newtheoremstyle, or place the remark in its own box; for boxed text see the framed environment in LaTeX. Paragraph layout around remarks is covered in indentation in LaTeX.
Frequently asked questions
How do I write a note in LaTeX?
Use the same mechanism as a remark: under \theoremstyle{remark}, declare \newtheorem*{note}{Note} and write \begin{note} ... \end{note}. The manual’s own remark-style example declares Remark and Note side by side, with a numbered Case.
How do I write the end of a proof in LaTeX?
The proof environment from amsthm adds the QED symbol automatically, and the manual describes an optional argument to substitute the heading. Details and placement fixes are in the end-of-proof symbol guide.
What does ( do in LaTeX?
( opens inline math mode and ) closes it, for formulas that are part of a paragraph. Overleaf’s Mathematical expressions page lists $...$ and \begin{math}...\end{math} as equivalent, and says the choice is a matter of taste. [ ... ] instead starts display math, for expressions set on separate lines.
Does anyone use LaTeX anymore?
This page cites no usage statistics, so it makes no popularity claim. What the sources show is current documentation: Overleaf maintains theorem and math guides, and the AMS amsthm manual is distributed on CTAN with the AMS document classes.
Sources (official documentation)
- Overleaf, Theorems and proofs, read 2026-11-07.
- Overleaf, Mathematical expressions, read 2026-11-07.
- American Mathematical Society, Using the amsthm package, amscls documentation on CTAN (PDF), read 2026-11-07.
