Questions related to rhotic and non-rhotic accents.
Rhoticity in an English-speaker's accent refers to the situations in which he or she pronounces the consonant /r/. To simplify, in rhotic English, the r is generally pronounced in all situations; in non-rhotic English, it is not pronounced before consonant sounds (e.g. burn) or at the end of a syllable (e.g. beer). The term was first defined by British phonetician John C. Wells in 1968.
Rhoticity is one of the primary ways in which different accents of English are classified. Rhotic speech includes most american-english, canadian-english, hiberno-english, indian-english, scottish-english, and English as spoken in the southwest of England. Non-rhotic speech is characteristic of the rest of the world, including australian-english, caribbean-english (except Barbados), new-zealand-english, singapore-english and south-african-english, the English of Wales and most of England outside the southwest, and aave, Southern, New England, and New York vernaculars in the United States.
The division is neither binary nor static. The degree of rhoticity varies even among speakers of the same dialect, and indeed an individual's rhoticity may vary from word to word. Evidence is also ample that r-fulness or r-lessness has varied across dialects over time.