Linguists study the semantics ¹ and the grammar of languages to gain an understanding of the structure. Phonemes are the basic sounds that all languages are built on. Differences is pronunciation affect the meaning of words. The two phonemes "t" and "oy" are combined to make toy, but changing the pronounciation of the "t" to a "b" changes the menaing and make the word boy. Linguists estimate that there are about 100 different phonemes that humans can pronounce although no language is believe to use more than 80 phonemes. The English language only uses about 40 phonemes. Adults have difficulty pronouncing a phoneme when speaking a second language that does not exist in their first language.

The next level of language structure is morphemes which are the smallest units of meaning in a language. Usually morphemes contain two or more phonemes but I and A are exceptions to the rule. Not all words are single morphemes, words like bluebird contain two morphemes. An inflection is a special type of morpheme that is typically added to the beginning of end of a word. ed, s, ness, un, ing are all examples of inflections. Morphemes are the building blocks used to construct sentences. Linguists estimate that the English language contains over 50,000 morphemes.

Each language has a set of rules for making words and sentences. Phonological rules allow only certain combinations of phonemes to be used in word construction. These rules in English does not allows phonemes like "t" and "k" to be combined as "tk," but in Russian such combinations are common. Morphological rules control the formation and structure of words. Syntax specifies the way that words are arranged in phrases and sentences. All of the rules that govern the structure of language make up the grammar of a language. Prescriptive grammar is the abstract system of grammatical rules used in the proper language. In English contractions such as ain't do not follow prescriptive grammar. Descriptive grammar is the set of rules that apply to natural language. Structures such as the order of words in a phrase can change meaning without changing words because of descriptive grammar.

Sentence structure is studied by looking at noun and verb phrases seperately and then dividing the phrases further. From studying ambiguous phrases researchers realized that sentences have different levels of structure. Noam Chomsky examines sentences in terms of surface structure and deep structure. Surface structure is the actual words used in a phrase or sentence, so each sentence has one structure on this level. Deep structure is the meanings of the words in phrases or sentences, so each meaning of a sentence is a deep structure. Sentences with different surface structures can have the same deep structure. Analyzing sentences only at the surface level structure is called the syntactic approach. The syntactic approach recognizes that there are transformational grammar rules that determine with changes in the wording of a sentence are possible without changing the meaning of the sentence. Transformational rules help linguists understand how meaning is communicated in sentences.