questions. Fasold and Connor-Linton (2006), Falk (1978) and Hudson (2000) provide similar definitions for the two terms. O'Grady et al. (1384) don't mention the exact terms 'second' and 'foreign' language, but they emphasise on the role of learning environment in teaching non-native languages. So, the distinction between 'second language' and 'foreign language' is a geographical and environmental distinction. We can mention 'second-language situation' and 'foreign-language situation' as two situations of learning, not two kinds of languages. So a foreign language is not always a foreign language and a second language is not always a second language. Since the distinction is geographical, the two situations (learning second language and learning foreign language) can be considered as a continuum. At one extreme, we may find learners learning without external help and direction purely from exposure to the non-native language through living in the target language environment (second-language learning) and at the other we find learners learning the non-native language exclusively in language teaching setting and classrooms (foreign-language learning). A 'second language' usually has official status or a recognised function within a country which a foreign language has not and furthermore these two different situations frequently have important consequences to which attention has been drawn in some books. For example, Persian is a second language for Kurdish people, but not vice versa, because there is no Kurdish environment for Persian speakers who are learning Kurdish. On the other hand, English is a foreign language for both groups, because there is no contact between Kurdish and Persian people with English people. However, if an Iranian person goes to United States, then English becomes a second language for them. Thus, British immigrants to Iran learn Persian as a second language, and Persian speakers study English in Britain as a second language. Meanwhile, people in Kurdistan can speak of learning Kurdish by Persian speakers as a second rather than foreign language. The purposes of second-language learning are often different from foreign-language learning. Second language is needed for full participation in the political and economic life of the nation, because it is frequently the official language or one of two or more recognised languages. It may be the language needed for education. Among the purposes of foreign-language learning are traveling abroad, communication with native speakers, reading foreign literature or scientific and technical works. There are some major differences between foreign and second language teaching and learning. In