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Researchers who typeset equations in LaTeX usually need three things: the command for a symbol, the package it depends on, and the delimiters that make LaTeX read it as math. This guide gives all three, with direct answers to the questions that come up most: the difference between \approx and \sim, what \( does, how to make math symbols bold, and how to type the “belongs to” symbol.
What LaTeX math signs are used for in research
Journals in statistics, physics, computer science, engineering and the life sciences commonly accept or require LaTeX manuscripts, and every equation, variable and relation in them is typed as a command rather than picked from a menu. A “math sign” in this sense is any command that prints a mathematical symbol: relations (≈, ∈), Greek letters, operators, and set symbols. Each command is only valid in math mode, which is switched on by the delimiters described next.
Install or access
The commands on this page run in any standard LaTeX installation. Two routes need no setup beyond a browser or a TeX distribution:
- An online editor such as Overleaf, which compiles in the browser (see what Overleaf is).
- A local TeX distribution such as TeX Live or MiKTeX, with an editor of your choice.
Core symbols need no extra package. Some need one line in the preamble, for example \usepackage{amsmath}, \usepackage{amssymb} or \usepackage{bm}; the table in the next section shows which.
Step by step: typing a math sign
Step 1. Open math mode: what does \( do in LaTeX?
\( opens inline math and \) closes it. Text between them is typeset as a formula inside the running paragraph. According to Overleaf’s documentation, inline math can be written three ways, \(...\), $...$ or \begin{math}...\end{math}, and “they all work and the choice is a matter of taste”; the standard LaTeX form is \(...\).
For an expression that should sit on its own line rather than inside a paragraph, use display math: \[...\], \begin{displaymath}...\end{displaymath}, or \begin{equation}...\end{equation}. The equation environment gives numbered or unnumbered versions of the formula.
The value is \( \pi \approx 3.14 \) to two decimal places. \[ x \in A \]
Step 2. Choose the command
| I want to type | Command | Package needed | Related CASRAI guide |
|---|---|---|---|
| Approximately equal (≈) | \approx |
None (core LaTeX) | Therefore and related symbols |
| Similar to / distributed as (∼) | \sim |
None (core LaTeX) | Therefore and related symbols |
| Belongs to / element of (∈) | \in |
None (core LaTeX) | Subset symbols |
| Greek letters (γ, Ω, φ, δ) | \gamma, \Omega, \phi and \varphi, \delta |
None (core LaTeX) | Greek symbols in LaTeX |
| Bold Latin letters | \mathbf{...} |
None (core LaTeX) | Bold in LaTeX |
| Bold Greek letters and other symbols | \boldsymbol{...} |
amsmath | Bold in LaTeX |
| Bold symbols without loading all of amsmath | \bm{...} |
bm | Bold in LaTeX |
| Blackboard bold sets (ℝ, ℤ) | \mathbb{R} |
amssymb | Blackboard bold |
Overleaf’s symbol list notes that “some of the symbols require loading of the amssymb package,” so if a symbol that is not in the table fails to compile, check the package first.
Output and how to read it
What is the difference between ≈ and ∼?
\approx prints ≈ and reads as “approximately equal to”, for example \pi \approx 3.14. \sim prints ∼ and is a relation symbol whose meaning depends on the field: “is similar to”, “is distributed as” (a statistics convention, X \sim N(0,1)), or an equivalence or asymptotic relation. Using ∼ to mean “approximately” is common, but ≈ is clearer for numerical approximation because it cannot be confused with the other meanings. This distinction is a matter of notation convention rather than a rule enforced by LaTeX; check the target journal’s style if it defines its own.
How do I type the “belongs to” symbol?
Use \in inside math mode: \( x \in A \) prints “x ∈ A” and reads “x is an element of A” or “x belongs to A”. The Overleaf symbol list includes \in. The negation (not an element) is \notin and the reversed form “contains as a member” is \ni. For related set notation see subset symbols and set intersection.
How do I make mathematical symbols bold?
There are three commands, and they behave differently.
\mathbf{...}is core LaTeX. Overleaf’s fonts documentation shows it changing every character in its argument (its example is\mathbf{3x^2 \in R \subset Q}).\boldsymbol{...}comes from amsmath. The amsmath user guide says\mathbf“is commonly used to obtain bold Latin letters in math, but for most other kinds of math symbols it has no effect, or its effects depend unreliably on the set of math fonts that are in use”, and that\boldsymbolworks for a symbol “if (and only if) your current math font set includes a bold version of that symbol”. The same guide offers\pmb(“poor man’s bold”) as a last resort for symbols with no true bold version.\bm{...}comes from the bm package, which CTAN describes as defining “a command \bm which makes its argument bold”; the amsmath guide recommends it if you want\boldsymbolbehaviour without loading the whole of amsmath.
\( \mathbf{x} \) bold Latin letter
\( \boldsymbol{\alpha} \) bold Greek letter (amsmath)
\( \bm{\alpha} \) bold Greek letter (bm)
In practice, use \mathbf for vectors named with Latin letters and \boldsymbol or \bm when a Greek letter or other symbol must be bold.
Greek letters and the common variants
Overleaf’s list shows lowercase and capital pairs by capitalising the command name: \gamma and \Gamma, \delta and \Delta, \omega and \Omega, and \phi, \varphi and \Phi. The two lowercase phi forms print different glyphs, so use whichever your field or journal prefers consistently. More detail is in Greek symbols in LaTeX.
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
“Undefined control sequence” on a symbol or on \boldsymbol, \bm, \mathbb |
The package that defines the command is not loaded | Add \usepackage{amsmath}, \usepackage{bm} or \usepackage{amssymb} to the preamble |
| Error that a math command is “allowed only in math mode” | The command was typed in ordinary text | Wrap it in \( ... \) |
| Bold command has no visible effect on a Greek letter or operator | \mathbf does not affect most non-Latin symbols |
Use \boldsymbol or \bm |
Free alternatives
| Option | How you use it | More |
|---|---|---|
| Overleaf | Online editor; compile in the browser | What is Overleaf |
| TeX Live or MiKTeX | Local TeX distribution; compile on your own machine | Overleaf alternatives |
FAQ
What is the difference between ≈ and ∼ in LaTeX?
\approx means approximately equal; \sim is a relation whose meaning (similar to, distributed as, asymptotic) depends on the field.
What does \( do in LaTeX?
It starts inline math mode, which ends at \).
How do I make mathematical symbols bold in LaTeX?
Use \mathbf for Latin letters, and \boldsymbol (amsmath) or \bm (bm package) for Greek letters and other symbols.
How do I type the belongs to symbol in LaTeX?
Type \in in math mode; \notin gives its negation.
Sources
- Overleaf, Mathematical expressions (read 2026-11-07).
- Overleaf, List of Greek letters and math symbols (read 2026-11-07).
- Overleaf, Mathematical fonts (read 2026-11-07).
- CTAN, bm package (read 2026-11-07).
- American Mathematical Society, User’s Guide for the amsmath Package, section 9.3 (read 2026-11-07).
