Phonetics (from the Greek word φωνή, phone which means 'sound' or 'voice') is the science of the sounds of human speech. Someone who is an expert in phonetics is called a phonetician.

Phonetic theory regards the nature of sounds in speech (called phones) and how they are made, heard and thought of. Phonology, which came from it, studies sound systems and sound units (such as phonemes and distinctive features). Phonetics is one of the two parts of orthographical linguistics, the other part being spelling, differing from grammar and lexis.