Phonetics (from the Greek word φωνή, phone meaning 'sound, voice') is the study of the sounds of human speech. It is concerned with the actual properties of speech sounds (phones), and their production, audition and perception, as opposed to phonology, which is the study of sound systems and abstract sound units (such as phonemes and distinctive features). Phonetics deals with the sounds themselves rather than the contexts in which they are used in languages. Discussions of meaning (semantics) do not enter at this level of linguistic analysis.
Phonetics has three main domains:
1- Articulatory phonetics, concerned with the positions and movements of the lips, tongue, vocal tract and folds and other speech organs in producing speech;
2- Acoustic phonetics, concerned with the properties of the sound waves and how they are received by the inner ear
3- Auditory phonetics, concerned with speech perception, principally how the brain forms perceptual representations of the input it receives.
Phonetics was studied as early as 2,500 years ago in ancient India, with Pāṇini's account of the place and manner of articulation of consonants in his 5th century BCE treatise on Sanskrit. The major Indic alphabets today, except Tamil script, order their consonants according to Pāṇini's classification