Both in Latvia and in the world the concept of first language, second language and foreign language exist, but often there is a different understanding of them, especially with regard to the terms of the second language and foreign language, therefore it is useful to find out how the concepts of the first language, the second language and the foreign language are understood and used in the world.These terms are used in language learning, in educational theory and in sociology.Since depending on different situations language may have different language status, the aim of the article is to ascertain how the concepts of first language, second language and foreign language are understood outside of Latvia.The main method used in this research is the study of scientific literature, summarizing the most significant works of foreign authors, which explain the terms of the first language, the second language and the foreign language.The study found that the term second language is used extensively outside of Latvia, describing the second language acquired chronologically, the majority language that the minorities know as well as any language other than the mother tongue.The results obtained in the study make it possible to compare the comprehension and use of the concepts of the first language, the second language and the foreign language outside Latvia and in Latvia.The author of the article has publications on the use of terms of the first language, the second language and the foreign language in Latvia and in exile conditions.Thus, the results obtained allow us to conclude that foreign researchers sometimes choose the term second language as a convenient and overarching term to designate both foreign language and second language in the sense understood by the Latvian researchers, even though also abroad these are two distinct concepts, however, in Latvia the distinction between them is more specific.