English phonology
Like many languages, English has wide variation in pronunciation, both historically and from dialect to dialect. In general, however, the regional dialects of English share a largely similar (though not identical) phonological system.
Phonological analysis of English often concentrates on, or uses as a reference point, one or more of the prestige or standard accents, such as Received Pronunciation for England, General American for the United States, and General Australian for Australia. Nevertheless, many other dialects of English are spoken, which do not necessarily descend from any of these standardised accents. Information about these standardised accents functions only as a limited guide to all of English phonology, which one can later expand upon once one becomes more familiar with some of the many other dialects of English that are spoken.
Phonemes
A phoneme of a language or dialect is an abstraction of a speech sound or of a group of different sounds which are all perceived to have the same function by speakers of that particular language or dialect. For example, the English word "through" consists of three phonemes: the initial "th" sound, the "r" sound, and an "oo" vowel sound. Notice that the phonemes in this and many other English words do not always correspond directly to the letters used to spell them (English orthography is not as strongly phonemic as that of certain other languages).