Comparison of General American and Received Pronunciation

One aspect of the differences between American and British English is that of specific word pronunciations, as described in American and British English pronunciation differences. However, there are also differences in some of the basic pronunciation patterns between the standard dialects of each country. The standard varieties for each are in fact generalizations: for the U.S., a loosely defined spectrum of unmarked varieties called General American (abbreviated "GA") and, for Britain, a collection of prestigious varieties most common in southeastern England, ranging from upper- to middle-class Received Pronunciation accents (often classified along a continuum with local Estuary English), which together here are abbreviated "RP". However, other regional accents in each country also show differences, for which see regional accents of English speakers.
Received Pronunciation has been the subject of many academic studies, and is frequently used as a model for teaching English to foreign learners. The widely repeated claim that only about two percent of Britons speak RP is no more than a rough estimate and has been questioned by several writers, most notably by the phonetician J. Windsor Lewis.