Abstract
When it comes to learning a second language, no matter what age, almost every publication talks about individual differences that lead the learners to success. It is possible to say that the age factor is the most significant of these. Various elements occur as a result of individual differences: The rate of acquisition, ultimate achievement and the processes involved in language acquisition are important ones affected by differences among learners, particularly their age. The present work deals mainly with the age issue in second language acquisition, along with other factors related to individual differences, which are often treated in psychological positions. The data were obtained from a literature search. Looking at the written literature in the field, it has been found that the onset of second language acquisition and the final accomplishment are also the two titles that scholars have studied very much. The question of whether a critical period addressed language acquisition exists is a controversial one in the scientific world. However, even though there are no well-delineated age restrictions ready for attaining native or native-like proficiency in a second language, the period (age) at which one starts has been shown to correlate with ultimate proficiency.