Dialects can be defined as "sub-forms of languages which are, in general, mutually comprehensible." English speakers from different countries and regions use a variety of different accents (systems of pronunciation), as well as various localized words and grammatical constructions; many different dialects can be identified based on these factors. Dialects can be classified at broader or narrower levels: within a broad national or regional dialect, various more localized sub-dialects can be identified, and so on. The combination of differences in pronunciation and use of local words may make some English dialects almost unintelligible to speakers from other regions.
The major native dialects of English are often divided by linguists into three general categories: the British Isles dialects, those of North America, and those of Australasia. Dialects can be associated not only with place, but also with particular social groups. Within a given English-speaking country, there will often be a form of the language considered to be Standard English – the Standard Englishes of different countries differ, and each can itself be considered a dialect. Standard English is often associated with the more educated layers of society, as well as more formal registers.