A graphic sign established by convention to represent a magnitude, a number, an operation, a relationship, a mathematical or logical entity of a given nature.

- Symbols sometimes resemble the objects they symbolize, as does the symbol for the measure of an angle (∠), although this is rarely the case.
- Mathematical symbols are generally written forms that have been established through years or even centuries of use.

### Examples

Certain symbols are *literal*; they are letters that represent or correspond to a value, magnitude or operation; for example :

- letters in units of measure, such as m or cm;
- unknowns, such as the letter
*x*in the equation*x*+ 7 = 12 ; - given numbers, such as
*a*and*b*in the relationship*a*+*b*=*b*+*a*.

Certain symbols are *numerical* :

- Roman numerals, such as I, V, X, L, C, D, M;
- the ten Arabic numerals 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

Certain symbols are *grouping* symbols :

- braces: { };
- brackets: [ ];
- parentheses: ( ).

Certain symbols are graphics that resemble the concepts they symbolize; for example :

- the symbol for the relationship of perpendicularity, ⊥;
- the symbol for the relationship of parallelism, //;
- the symbol that identifies an angle, ∠;
- the symbol for the relationship of approximate equality, ≈.