A minimal pair consists of two words distinguished by a single phoneme. The famous example is ship and sheep, where the two English words are distinguished only by the vowel; ship has a short, lax, high front unrounded vowel, while sheep has a longer, tense high front unrounded vowel.
In language learning, discrimination - the ability to differentiate between similar sounds, for example, is an important precursor to accurate reproduction.
The prelude to mimicry being the precise attention to the phonological input of the message regardless of the informational content.
The contrastive analysis hypothesis (see Robert Lado and Charles Fries) predicts learning difficulty with target language sounds which are absent or differently distributed in the native language; a careful comparison of the two languages is necessary to determine which minimal pairs should be presented for practice by learners.