 In phonology, minimal pairs are pairs of words or phrases in a particular language that differ in only one phonological element and have distinct meanings. Minimal pairs constitute a discovery procedure for the phonemes in a language. It works as follows. Compare two items, let's say two words. Here are four such present-day English pairs in their orthographical form. Then identify and count the number of sound segments in both items of the pair. If the number of identified segments is different, the items in question do not constitute a minimal pair. If both items exhibit the same number of segments, go to step two. Now look at the segments. If only one segment is different, we can proceed. Otherwise, we don't have a minimal pair. Step three compares the meanings. If both items mean the same, despite some odd pronunciation effects as in hill versus hill, they do not constitute a minimal pair and the two different sounds must be members of the same phoneme. However, if the meaning is different, we have a minimal pair and the two sounds in question must be members of two distinct phonemes. Simple, isn't it? Just study this animated flowchart to see a shorthand version of this well-known phonemic discovery procedure, which admittedly requires a solid background in phonetics and phonology.