English as a Second Language (ESL) is generally English that individuals must learn, in addition to another language they speak, to take part in the life of their country. An example might be Spanish-speaking Mexican Americans who learn English in the United States.
English as a Foreign Language (EFL) is usually the English learned by individuals who have no other contact with the language. For example, many adult Chinese are today learning English as a foreign language.
English for Special Purposes (ESP) is usually designed to give some specific English skills in, for example, trades, business or other professions.
A World Language
This chapter introduces the scope of international English.
Competence aims in focus:
The aims of the studies are to enable pupils to
Ages of English: Timeline (BBC)
Varieties of English (E.L. Easton)