Minimal pairs are pairs of words that differ only very slightly, or, as linguists say, by one phonological unit, although that's just jargon. Case in point, they can differ:
- by one sound (linguist jargon: phoneme) - e.g. English "bat" and "pat", French "rue" and "roux"
- by one tone (linguist jargon: toneme) - languages like Mandarin and Vietnamese have tones
- by the length of a sound (linguist jargon: chroneme) - e.g. Italian "vile" and "ville",
- when the stress is put on different syllables - e.g. English "address" (noun and verb), Greek "παπά" (priest) and "πάπα" (Pope).
For linguists, minimal pairs are most often used to "prove" that two phonological units are different within a language.
But, for the average person, minimal pairs have a more practical use - language learning! You can make tests with them: being given the audio pronunciation of a word, you'll have to choose the word that you think was pronounced. Remember, the more similar the sounds, the harder it is to get it correct! Also, note that this "test" is made for both words, so you get to hear both pronunciations. With time, after testing yourself consistently, you'll be able to better distinguish the seemingly similar sounds of your target language.