Applied linguistics is a realm of study that examines language-related problems, often in conjunction with education, psychology, anthropology and sociology.
When considered in relation to TESOL, applied linguistics is a related, though not identical field. Whereas TESOL is concerned with imparting the conventions of the English language to speakers of other languages, applied linguistics is focused on the theoretical and empirical aspects of real world problems, such as bilingual education, literacy and translation.
Because the goals of applied linguistics differ from that of standard TESOL, different credentials are required. An individual looking to work in a TESOL capacity would be fit with an English-teaching degree, such as the CELTA, but a linguist would be better suited with a master’s degree in applied linguistic, inlcuding a TESOL concentration if he or she also wishes to teach the language.