**Algebra** is one of the main branches of mathematics, covering the study of structure, relation and quantity. Algebra studies the effects of adding and multiplying numbers, variables, and polynomials, along with their factorization and determining their roots. In addition to working directly with numbers, algebra also covers symbols, variables, and set elements. Addition and multiplication are general operations, but their precise definitions lead to structures such as groups, rings, and fields.

See also: Equation |

An algebraic equation is an equation involving only algebraic expressions in the unknowns. These are further classified by degree.

- Linear equation – algebraic equation of degree one.
- Polynomial equation – equation in which a polynomial is set equal to another polynomial.
- Transcendental equation – equation involving a transcendental function of one of its variables.
- Functional equation – equation in which the unknowns are functions rather than simple quantities.
- Differential equation – equation involving derivatives.
- Integral equation – equation involving integrals.
- Diophantine equation – equation where the unknowns are required to be

- Fundamental theorem of algebra – states that every non-constant single-variable polynomial with complex coefficients has at least one complex root. This includes polynomials with real coefficients, since every real number is a complex number with an imaginary part equal to zero.
- Equations – equality of two mathematical expressions
- Linear equation – an algebraic equation with a degree of one
- Quadratic equation – an algebraic equation with a degree of two
- Cubic equation – an algebraic equation with a degree of three
- Quartic equation – an algebraic equation with a degree of four
- Quintic equation – an algebraic equation with a degree of five
- Polynomial – an algebraic expression consisting of variables and coefficients
- Inequalities – a comparison between values
- Functions – mapping that associates a single output value with each input value
- Sequences – ordered list of elements either finite or infinite
- Systems of equations – finite set of equations
- Vectors – element of a vector space
- Matrix – two dimensional array of numbers
- Vector space – basic algebraic structure of linear algebra
- Field – algebraic structure with addition, multiplication and division
- Groups – algebraic structure with a single binary operation
- Rings – algebraic structure with addition and multiplication