Greek Letters

Lowercase commands are the letter name; capitalize the first letter for uppercase (\gamma → γ, \Gamma → Γ). Letters that look like Latin capitals — A for alpha, B for beta — have no command; just type the letter. Two habits worth forming: \varepsilon over \epsilon and \varphi over \phi. The var forms are what you see in every textbook; the plain forms are the lunate variants most people don't want.

Full alphabet with rendered output: Greek letters in LaTeX.

Binary Operators

These sit between two operands and get operator spacing automatically. Use \cdot for multiplication in running math — \times is for cross products, dimensions (3 × 4 matrix), and scientific notation.

Relations

Relations compare two things. The lookalikes have distinct meanings, and reviewers notice: \approx for numerical closeness, \sim for "distributed as" or asymptotic equivalence, \simeq and \cong for structural sameness, \equiv for identities and modular arithmetic.

Arrows

\to and \rightarrow produce the identical arrow. Type \to — it's shorter, and function signatures like f: A \to B read better in source. For logical implication in displayed math, amsmath's \implies and \iff add the surrounding space that \Rightarrow alone doesn't.

Sets and Logic

One opinionated pick: \varnothing (amssymb) over \emptyset for the empty set. \emptyset renders as a narrow struck zero; \varnothing is the round symbol that matches ∅ as you'd draw it on a board.

Calculus and Big Operators

Big operators take limits with _ and ^: \sum_{i=1}^{n}. In display math the limits sit above and below; inline they move to the side so the line height survives.

Delimiters

Delimiters don't grow on their own. Wrap tall content in \left and \right — \left\lfloor \frac{n}{2} \right\rfloor — and they size to fit. For norms and absolute values, prefer \lVert/\rVert and \lvert/\rvert over bare \| and |: the paired forms tell LaTeX which side is which, so the spacing comes out right.

Accents

Dots

The rule: \ldots sits on the baseline and goes with commas — a_1, \ldots, a_n. \cdots is centered and goes between operators — a_1 + \cdots + a_n. If you load amsmath, plain \dots picks the right one from context, which is one less thing to remember.

Text-Mode Symbols and Reserved Characters

LaTeX reserves seven characters for its own syntax: # $ % & _ { } — plus ~, ^, and \ which have special roles. Typing them literally either breaks compilation or silently eats your text (an unescaped % comments out the rest of the line). Here is the escape for each:

Miscellaneous

Frequently asked questions

If a symbol command errors out, the fix is usually in Undefined control sequence, explained. For letter styles like ℝ, 𝒜, and 𝔤, see mathbb, mathcal, and mathfrak; for worked examples in context, see mathematical symbols in LaTeX.