Linguistic proficiency is the ability of an individual to speak or perform in an acquired language. Thus, native speakers of a language can be fluent without being considered proficient. Native-level fluency is estimated to be between 20,000 - 40,000 words, but basic conversational fluency might only require as little as 3,000 words. (Wikipedia ) In assessing Linguistic performance speech usually contains lots of mistakes and hesitations, but that doesn 't mean that the competence underlying that speech is flawed. Since competence can 't be observed directly, linguists use linguistic performance as a basis for making hypotheses and drawing conclusions about what competence must be like. However, in most cases they try to disregard performance factors (the inevitable speech errors, incomplete utterances, and so on) and focus on consistent patterns in their study of linguistic competence.
Five Areas of Linguistics According to the Center for Applied Linguistics (CAL), formal linguistics includes five principal areas of study: phonetics, the study of language, sounds and their physical properties (how sounds are produced by the vocal tract and how sounds are perceived by others); phonology, analyzing how sounds functions in a given language or dialect, morphology, the study the structure of words; syntax, the study of structure of sentences, and semantics, the study of meaning in a language. (Bailey 2006; Kamhi-Stein 2009) as cited by( Richards, 2011 )says that we