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.
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 Asampurna Melakarta (transliterated as Asaṃpūrṇa Mēḷakarta) scheme is the system of 72 ragas (musical scales) originally proposed in the 17th century by Venkatamakhin in his Chaturdanda Prakasikha. This proposal used scales with notes that do not conform to the sampurna raga system. Skipped notes or repeated notes, etc., were used in some of the ragas. Some of the ragas of any Melakarta system will use Vivadi swaras (discordant notes). The original system is supposed to avoid such ill-effects and was followed by the Muthuswami Dikshitar school. The naming of the original system followed Katapayadi system. Muthuswami Dikshitar's compositions use the name of these ragas in the lyrics of the songs and is still referred to by those names even in radio / TV announcements of these songs.
Later Govindacharya came up with a more mathematical and regular system of 72 ragas, which is currently considered fundamental ragas (musical scales) in Carnatic music (South Indian classical music). These melakarta ragas were sampurna ragas. Some of the names of the ragas had to be modified to fit into the Katapayadi system.