Variable
In more advanced mathematics, a variable is a symbol that denotes a mathematical object, which could be a number, a vector, a matrix, or even a function. In this case, the original property of "variability" of a variable is not kept (except, sometimes, for informal explanations).
Similarly, in computer science, a variable is a name (commonly an alphabetic character or a word) representing some value represented in computer memory.
Convention
François Viète introduced at the end of 16th century the idea of representing known and unknown numbers by letters, nowadays called variables, and of computing with them as if they were numbers, in order to obtain, at the end, the result by a simple replacement. François Viète's convention was to use consonants for known values and vowels for unknowns.[3]
In 1637, René Descartes "invented the convention of representing unknowns in equations by x, y, and z, and knowns by a, b, and c".[4] Contrarily to Viète's convention, Descartes' one is still commonly in use.
Identifiers referencing a variable
An identifier referencing a variable can be used to access the variable in order to read out the value, or alter the value, or edit the attributes of the variable, such as access permission, locks, semaphores, etc.
Variable: ABSTRACTION
Attribues: BINDING
- Name
- Type
- Value
- Address
In Programming Languages:
Scope is an important part of the name resolution of a variable.
Extent, on the other hand, is a runtime (dynamic) aspect of a variable.
