In generative syntax, binding refers to a relation in which the reference of a certain element is dependent on the reference of another element. Especially, it refers to that an element is coindexed with its antecedent which c-commands it, hence it is bound by the antecedent.
(i) All(v)[ ... v ... ] (ii) Exists(v)[ ... v ... ]
In the following formula only the first occurrence of x is bound by All but not the second (which is not in the scope of All):
(iii) All(x)[P(x) -> Q(y)] & R(x)
Gamut, L.T.F. 1991. Logic, language, and meaning. Chicago: University of Chicago Press.