A foreign language is a language that is not an official language of, nor typically spoken in, a specific country. Native speakers from that country usually need to acquire it through conscious learning, such as through language lessons at school, self-teaching, or attending language courses. A foreign language might be learned as a second language; however, there is a distinction between the two terms. A second language refers to a language that plays a significant role in the region where the speaker lives^{[citation needed]}, whether for communication, education, business, or governance. Consequently, a second language is not necessarily a foreign language.

Children who learn more than one language from birth or at a very young age are considered bilingual or multilingual. These children can be said to have two, three, or more mother tongues, meaning these languages would not be considered foreign to them, even if one language is a foreign language for the majority of people in the child's birth country. For instance, a child learning English from their English parent and Irish at school in Ireland can speak both English and Irish, but neither is a foreign language for them. This situation is common in countries like India, South Africa, or Canada, which have multiple official languages.

In general, it is believed that children have an advantage in learning foreign languages compared to adults. However, studies have shown that pre-existing knowledge of language and grammar rules, as well as a superior ability to memorize vocabulary, may benefit adults when learning foreign languages.

Most schools around the world teach at least one foreign language and most colleges and high schools require foreign language before graduation. By 1998, nearly all pupils in Europe studied at least one foreign language as part of their compulsory education, the only exception being Ireland, where primary and secondary schoolchildren learn both Irish and English, but neither is considered a foreign language (although Irish pupils do study a third European language). On average in Europe, at the start of foreign-language teaching, learners have lessons for three to four hours a week. Compulsory lessons in a foreign language normally start at the end of primary school or the start of secondary school. In Luxembourg, Norway and Malta, however, the first foreign language is studied at age six, and in Flanders at age 10. In Wales, all children are taught Welsh from the first year of primary school. The Welsh language is also compulsory up to the age of 16, although a formal GCSE qualification is optional.

In some countries, learners have lessons taken entirely in a foreign language: for example, more than half of European countries with a minority/regional language community use partial immersion to teach both the minority and the state language. This method is also highly used in Canada, wherein anglophone students spend all of most of their lessons learning the materials in French.

In 1995, the European Commission's White Paper on Education and Training emphasised the importance of schoolchildren learning at least two foreign languages before upper secondary education. The Lisbon Summit of 2000 defined languages as one of the five key skills.^{[citation needed]}

Despite the high rate of foreign-language teaching in schools, the number of adults claiming to speak a foreign language is generally lower than might be expected. This is particularly true of native English speakers: in 2004 a British survey by recruitment firm Office Angels showed that fewer than one in 10 UK workers could speak a foreign language and that less than 5% could count to 20 in a second language. In 2012, a European Commission survey found that 61% of respondents in the UK were unlikely to speak any language other than their mother tongue (page 5).

Since the 1990s, the Common European Framework of Reference for Languages has tried to standardise the learning of languages across Europe.