The surface structure (in the theory of transformational generating grammars ) is one way of describing the syntactic structure of a sentence.
A surface structure, which is a representation of a sentence at the level of surface syntax , is opposed to a depth structure , as a representation at the level of deep syntax. The surface structure is obtained from the deep structure as a result of applying special formal rules - transformations.
The formal way of writing the surface structure and the deep structure is the tree of direct components, however, while the deep structure is closer to the description of the meaning of the sentence, the surface structure better reflects the lexical composition, syntactic relations and linear order of the lexemes of a particular sentence in its phonetic-phonological or spelling incarnation. Therefore, sometimes the term “surface structure” is also called the very concrete sentence corresponding to the given structure.