 Model theory can be regarded as the product of Hilbert’s methodology of metamathematics and the algebra of logic tradition, represented specifically by the results due to Löwenheim and Skolem. But it was Tarski who gave the discipline its classical foundation. Model theory is the study of the relations between a formal language and its interpretation in “realizations” (that is, a domain for the variables of the language together with an interpretation for its primitive signs). If the interpretation happens to make a sentence of the language state something true, then the interpretation is a model of the sentence (see the entry on  model theory).  Models consist basically of algebraic structures, and model theory became an autonomous mathematical discipline with its roots not only in the algebra of logic but in abstract algebra (see Sinaceur 1999).