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This category contains definitions related to Variables.
Related results can be found in Category:Variables.

A variable is a label which is used to refer to an unspecified object.

A variable can be identified by means of a symbol, for example:

$x, y, z, A, B, C, \phi, \psi, \aleph$

It is often convenient to append a subscript letter or number to distinguish between different objects of a similar type:

$a_0, a_1, a_2, \ldots, a_n; S_\phi, S_{\phi_x}, \ldots$

The type of symbol used to define a variable is purely conventional.

Particular types of object, as they are introduced, frequently have a particular range of symbols specified to define them, but there are no strict rules on the subject.