Language & WorldMental model
'A language is a dialect with an army and navy.'
Popularised in 1945 by Yiddish scholar Max Weinreich, the line sums it up: whether something is called a language or a dialect is decided by politics, not linguistics. Danish, Norwegian and Swedish are largely mutually intelligible yet count as three. Mandarin and Cantonese are not, yet count as Chinese 'dialects'. Swiss German is a 'dialect' northern Germans barely understand.
Useful: When someone asks 'Is that a language or a dialect?', ask back: 'Politically or linguistically?'
Source: en.wikipedia.org