A phoneme is the smallest contrastive segment in a language. Phonemes, by themselves, do not possess any meaning. However, they are contrastive. In other words, by changing a phoneme, one can change the meaning of a word. The phoneme /b/ does not possess any meaning. However, if we take word like pin and change the first phoneme to /b/, we change the word to bin. This changes the meaning from an object that is like a needle (pin) to an object that is like a box (bin). Phonemes function as building blocks and allow us to build words.