In linguistics, binding is the phenomenon in which anaphoric elements such as pronouns are grammatically associated with their antecedents.^{[citation needed]} For instance in the English sentence "Mary saw herself", the anaphor "herself" is bound by its antecedent "Mary". Binding can be licensed or blocked in certain contexts or syntactic configurations, e.g. the pronoun "her" cannot be bound by "Mary" in the English sentence "Mary saw her". While all languages have binding, restrictions on it vary even among closely related languages. Binding has been a major area of research in syntax and semantics since the 1970s and, as the name implies, is a core component of government and binding theory.

The following sentences illustrate some basic facts of binding. The words that bear the index i should be construed as referring to the same person or thing.

These sentences illustrate some aspects of the distribution of reflexive and personal pronouns. In the first pair of sentences, the reflexive pronoun must appear for the indicated reading to be possible. In the second pair, the personal pronoun must appear for the indicated reading to be possible. The third pair shows that at times a personal pronoun must follow its antecedent, and the fourth pair further illustrates the same point, although the acceptability judgement is not as robust. Based on such data, one sees that reflexive and personal pronouns differ in their distribution and that linear order (of a pronoun in relation to its antecedent or postcedent) is a factor influencing where at least some pronouns can appear. A theory of binding should be capable of predicting and explaining the differences in distribution seen in sentences like these. It should be able to answer questions like: What explains where a reflexive pronoun must appear as opposed to a personal pronoun? When does linear order play a role in determining where pronouns can appear? What other factor (or factors) beyond linear order help predict where pronouns can appear?

The following three subsections consider the binding domains that are relevant for the distribution of pronouns and nouns in English. The discussion follows the outline provided by the traditional binding theory (see below), which divides nominals into three basic categories: reflexive and reciprocal pronouns, personal pronouns, and nouns (common and proper).

When one examines the distribution of reflexive pronouns and reciprocal pronouns (which are often subsumed under the general category of "anaphor"), one sees that there are certain domains that are relevant, a "domain" being a syntactic unit that is clause-like. Reflexive and reciprocal pronouns often seek their antecedent close by, in a binding domain that is local, e.g.

These examples illustrate that there is a domain within which a reflexive or reciprocal pronoun should find its antecedent. The a-sentences are fine because the reflexive or reciprocal pronoun has its antecedent within the clause. The b-sentences, in contrast, do not allow the indicated reading, a fact illustrating that personal pronouns have a distribution that is different from that of reflexive and reciprocal pronouns. A related observation is that a reflexive and reciprocal pronoun often cannot seek its antecedent in a superordinate clause, e.g.

When the reflexive or reciprocal pronoun attempts to find an antecedent outside of the immediate clause containing it, it fails. In other words, it can hardly seek its antecedent in the superordinate clause. The binding domain that is relevant is the immediate clause containing it.

Personal pronouns have a distribution that is different from reflexive and reciprocal pronouns, a point that is evident with the first two b-sentences in the previous section. The local binding domain that is decisive for the distribution of reflexive and reciprocal pronouns is also decisive for personal pronouns, but in a different way. Personal pronouns seek their antecedent outside of the local binding domain containing them, e.g.