The following is a glossary of math symbols. I wrote it as part of my early grad studies in software engineering. It's meant to assist me in understanding discrete mathematics.
Addition: $+$
Subtraction: $-$
Multiplication: $\times$
Division: $\div$
Square Root: $\sqrt{x}$
Empty Set: $\emptyset$
Union: $\cup$ (a union is the result of combining two sets)
Intersection: $\cap$ (an intersection is the result of finding common elements between two sets)
Difference: $\setminus$ (a difference is the result of removing elements from one set that are also in another set, for example $A \setminus B$)
Symmetric Difference: $\Delta$ (a symmetric difference is the result of combining the differences between two sets)
Set Membership: $\in$ (an element is a member of a set, for example $x \in {1, 2, 3}$. Read as "x is an element of the set {1, 2, 3}")
Set Non-Membership: $\notin$ (an element is not a member of a set)
Negation: $\neg$ (a negation is the opposite of a statement, for example $\neg P$)
Conjunction: $\land$ (a conjunction is the result of combining two statements with "and", for example $P \land Q$)
Disjunction: $\lor$ (a disjunction is the result of combining two statements with "or", for example $P \lor Q$)
Implication: $\implies$ (an implication is the result of combining two statements with "if...then", for example $P \implies Q$)
Biconditional: $\iff$ (a biconditional is the result of combining two statements with "if and only if", for example $P \iff Q$)
Equivalence: $\equiv$ (an equivalence is the result of combining two statements with "is equivalent to", for example $P \equiv Q$)
Existential Qualification: $\exists$ (an existential qualification is the result of combining a statement with "there exists", for example $\exists x \in \mathbb{R}$)
Universal Qualification: $\forall$ (a universal qualification is the result of combining a statement with "for all", for example $\forall x \in \mathbb{R}$)
Uniqueness Qualification: $\exists!$ (a uniqueness qualification is the result of combining a statement with "there exists exactly one", for example $\exists! x \in \mathbb{R}$)
Letters in the "blackboard bold" font are used to denote mathematical sets and numbers.
Natural Numbers: $\mathbb{N}$
Integers: $\mathbb{Z}$
Rational Numbers: $\mathbb{Q}$
Real Numbers: $\mathbb{R}$
Complex Numbers: $\mathbb{C}$
These are Greek letters that commonly appear in math. They are listed as uppercase, then lowercase. Optionally, a variant version follows as a third symbol.
Alpha: $\Alpha \alpha$
Beta: $\Beta \beta$
Gamma: $\Gamma \gamma$
Delta: $\Delta \delta$
Epsilon: $\Epsilon \epsilon$
Zeta: $\Zeta \zeta$
Eta: $H \eta$
Theta: $\Theta \theta \vartheta$
Iota: $I \iota$
Kappa: $K \kappa \varkappa$
Lambda: $\Lambda \lambda$
Mu: $M \mu$
Nu: $N \nu$
Xi: $\Xi \xi$
Omicron: $O o$
Pi: $\Pi \pi \varpi$
Rho: $P \rho \varrho$
Sigma: $\Sigma \sigma \varsigma$
Tau: $T \tau$
Upsilon: $\Upsilon \upsilon$
Phi: $\Phi \phi \varphi$
Chi: $X \chi$
Psi: $\Psi \psi$
Omega: $\Omega \omega$