The word Naadi in Tamil means "in search of". As a person goes in search of the details in the palm leaves about his entire life from birth to death, this system of Astrology came to be called as Naadi Astrology or Naadi Shastra. Each Naadi is made up of a particular "Ola" i.e "palm leaf" of a person and his/her life details and predictions are recorded on it in 'Vatta Ezhutthu', a Tamil script with a sharp nail-like instrument called 'Ezhuttani. These palm leaves are preserved for a very long period by rubbing peacock oil on auspicious occasions. The inscriptions or records on these palm leaves are in ancient Tamil language in verse form and only specially trained Naadi Readers will be able to read and interpret them to us. The predictions contained in these palm leaves are accurate because they are pre-defined and pre-determined by the sages and cannot be altered or manipulated.

These palm leaves were initially preserved in Saraswathy Mahal Library in Thanjavur city in Tamilnadu Sate of India. Later the British sold these palm leaves to the locals. Persons belonging to a particular community specialized in Astrology bought these leaves. The astrological families in Vaitheeswarankoil, near Chidambaram in Tamilnadu also acquired some of these leaves. Vaitheeswarankoil is about kilometer from Chennai, the capital of Tamilnadu. These leaves have been handed down from generation to generation to make predictions.