What is a phoneme?

Definition
	A phoneme is the smallest contrastive unit in the sound system of a language.

Discussion
	Phonologists have differing views of the phoneme. Following are the two major views considered here:
	In the American structuralist tradition, a phoneme is defined according to its allophones and environments. In the generative tradition, a phoneme is defined as a set of distinctive features.

Comparison
	Here is a chart that compares phones and phonemes:
	A phone is … A phoneme is … One of many possible sounds in the languages of the world. A contrastive unit in the sound system of a particular language. The smallest identifiable unit found in a stream of speech. A minimal unit that serves to distinguish between meanings of words. Pronounced in a defined way. Pronounced in one or more ways, depending on the number of allophones. Represented between brackets by convention. Example: [b], [j], [o] Represented between slashes by convention. Example: /b/, /j/, /o/

Examples (English): Minimal pair
	Here are examples of the phonemes /r/ and /l/ occurring in a minimal pair:
	rip lip
	The phones [r] and [l] contrast in identical environments and are considered to be separate phonemes. The phonemes /r/ and /l/ serve to distinguish the word rip from the word lip.

Examples (English): Distinctive features
	Here are examples of the English phonemes /p/ and /i/ specified as sets of distinctive features:
	/p/ /i/
	-syllabic +consonantal -sonorant +anterior -coronal -voice -continuant -nasal+syllabic -consonantal +sonorant +high -low -back -round +ATR -nasal

See also
	What is phonology? Comparison of morpheme-morph-allomorph and phoneme-phone-allophone