In linguistics, free variation is the phenomenon of two (or more) sounds or forms appearing in the same environment without a change in meaning and without being considered incorrect by native speakers.
[3] The term remains in use, however, in studies focused primarily on language as systems (e.g. phonology, morphology, syntax).
[4] When phonemes are in free variation, speakers are sometimes strongly aware of the fact (especially if such variation is noticeable only across a dialectal or sociolectal divide), and will note, for example, that tomato is pronounced differently in British and American English (/təˈmɑːtoʊ/ and /təˈmeɪtoʊ/ respectively),[5] or that either has two pronunciations that are distributed fairly randomly.
In the case of different realizations of the same phoneme, however, free variation is exceedingly common and, along with differing intonation patterns, variation in realization is the most important single feature in the characterization of regional accents.
[1] English's deep orthography and the language's wide variety of accents often cause confusion, even for native speakers, on how written words should be pronounced.