Raivaru is a type of Maldivian traditional singing, where letters are swapped to be sung in a certain melody without accompaniment. In the early years of Maldivian civilization raivaru was merely a pastime amongst toddy vintners (raiverin) thus the name raivaru.
With the development of the Maldivian culture and the introduction of the ground rules of reading and writing (Adhabiyaath) and the improvement of the Dhivehi language, raivaru transformed from a simple to a very developed art and part of the Maldivian syllabus for learning of Dhivehi as a first language.
With the newly made rules of raivaru some basic rules were made on how the letters in a raivaru were arranged. Thus came into existence two main types of raivaru, first raivaru with six lines of words, the lines in a raivaru are called as "bas" so a raivaru with six lines or six sentences was called a "Ha bahuge raivaru" and the raivaru with three lines or three sentences was called as "Thin bahuge raivaru".
These were merely the ground rules, Raivaru is an art so fine that in a perfectly synchronized raivaru, a lot of features and conditions have to be met .