Teaching English as a second language (TESL) refers to teaching English to students whose first language is not English, usually offered in a region where English is the dominant language and natural English language immersion situations are adapt to be plentiful. In contrast, teaching English as a foreign language (TEFL) refers to teaching English to students whose first language is not English, usually in a region where English is not the dominant language and natural English language immersion situations are apt to be few.
The teaching profession has historically used different names for these two teaching situations; however, the more generic term teaching English to speakers of other languages (TESOL) is increasingly used to describe the profession. Both native speakers and non-native speakers successfully train to be English language teachers. The use of these various terms has led to confusion about the training options for both prospective students and for employers. Because there is no global standard for the training of English language teacher, it is important to look beyond the actual acronym/title to the components of the training program. There are many second language learning theories that aim to explain the way second language is learnt and which approach is the best. A brief explanation of these theories is the behaviorist theory, the cognitive theory, the critical period of hypothesis, and Natural order hypothesis. First of all is The Behaviorist Theory which the theory it is believed that the second language learning learner tries to imitate what he hears and practices the second language regularly to develop habits in the language. This theory also believes that learners try to relate their knowledge of the native language to the second language and this could lead to positive as well as negative results. However the imitation of one language with the other is not appreciated as this does not help