Mēḷakarta is a collection of fundamental ragas (musical scales) in Carnatic music (South Indian classical music). Mēḷakarta ragas are parent ragas (hence known as janaka ragas) from which other ragas may be generated. A melakarta raga is sometimes referred as mela, karta or sampurna as well, though the latter term is inaccurate, as a sampurna raga need not be a melakarta (take the raga Bhairavi, for example).
In Hindustani music the thaat is equivalent of Melakarta. There are 10 thaats in Hindustani music, though the commonly accepted melakarta scheme has 72 ragas.
Ragas must contain the following characteristics to be considered Melakarta.
The mēḷa system of ragas was first propounded by Raamamaatya in his work Svaramelakalanidhi c. 1550. He is considered the father of mela system of ragas. Later, Venkatamakhin, a gifted musicologist in the 17th century, expounded a new mela system known today as mēḷakarta in his work Chaturdandi Prakaasikaa. He made some bold and controversial claims and defined somewhat arbitrarily 6 svaras from the known 12 semitones, at that time, to arrive at 72 mēḷakarta ragas. The controversial parts relate to double counting of R2 (and similar svaras) and his exclusive selection of madyamas for which there is no specific reasoning (also known as asampurna melas as opposed to sampurna ragas). However, today the 72 mēḷakarta ragas use a standardized pattern, unlike Venkatamakhi's pattern, and have gained a significant following. Govindhacharya is credited with the standardization of rules and known for giving different names for standard ragas that have a different structure but the same swaras as those proposed by Venkatamakhi. The scales in this page are those proposed by Govindaacharya.
A hundred years after Venkatamakhin's time the Katapayadi sankhya rule came to be applied to the nomenclature of the mēḷakarta ragas. The sankhya associates Sanskrit consonants with digits. The digits corresponding to the first two syllables of the name of a raga, when reversed, give the index of the raga. Thus the scale of a mēḷakarta raga can be easily derived from its name.