What is a sentece?

A simple complete sentence consists of a subject and a predicate. The subject is typically a noun phrase, though other kinds of phrases (such as gerund phrases) work as well, and some languages allow subjects to be omitted. The predicate is a finite verb phrase: it's a finite verb together with zero or more objects, zero or more complements, and zero or more adverbials. See also copula for the consequences of this verb on the theory of sentence structure.