Minimal pair

In phonology, minimal pairs are pairs of words or phrases in a particular language, which differ in only one phonological element, such as a phoneme, toneme or chroneme^[ and have distinct meanings. They are used to demonstrate that two phones constitute two separate phonemes in the language.
Many phonologists in the middle part of the 20th century had a strong interest in developing techniques for discovering the phonemes of unknown languages, and in some cases setting up writing systems for these languages. The major work of Kenneth Pike on the subject has the title Phonemics: a technique for reducing languages to writing. The minimal pair was an essential tool in the discovery process, arrived at by substitution or commutation tests. Modern phonology is much less interested in such issues, and the minimal pair is consequently considered to be of little theoretical importance.
As an example for English vowels, the pair "let" + "lit" can be used to demonstrate that the phones [ɛ] (in let) and [ɪ] (in lit) do in fact represent distinct phonemes /ɛ/ and /ɪ/. An example for English consonants is the minimal pair of "pat" + "bat". The following table shows other pairs demonstrating the existence of various distinct phonemes in English. All the possible minimal pairs for any language may be set out in the same way.

word 1	word 2	IPA 1	IPA 2	note
pin	bin	/pɪn/	/bɪn/	initial consonant
rot	lot	/rɒt/	/lɒt/
thigh	thy	/θaj/	/ðaj/
zeal	seal	/ziːl/	/siːl/
bin	bean	/bɪn/	/biːn/	vowel
pen	pan	/pɛn/	/pæn/
hat	had	/hæt/	/hæd/	final consonant

Phonemic differentiation may vary between different dialects of a language, so that a particular minimal pair in one accent is a pair of homophones in another. This does not necessarily mean that one of the phonemes is absent in the homonym accent; merely that it is not contrastive in the same range of contexts.