The most fundamental of Hindu deities, is the Trinity of Brahma, Vishnu and Shiva - popular deities include Ganesha, Krishna, Hanuman and goddesses like Lakshmi, Durga,Saraswati.
Lord Shiva once gave two hills, which were active with His energy, to Saint Agasthiar. His disciple Idumbasuran carried the hills tied on either side of a big Brahmathandam towards the south. When he came to Thiruaavinankudi, he placed the hills down and took rest. Lord Muruga wanted the hills to be there permanently so he performed the following divine act. When Idumbasuran wanted to lift the hills again, he was unable to even move them. He was shocked to see a small boy standing on the top of the hill. He fought a war with the boy, but at last lost the battle. Then he realized it was Lord Muruga. As his ego was destroyed, he fell at the feet of Lord Muruga and requested that when devotees carry ‘Kavadi', they should be blessed with Food, Health, Wealth, Progeny, Devotion and Liberation.
'Kavadi' appears to be a word of Tamil origin - a combination of the words 'kavi' and 'adi'. 'Kavi' means 'saffron' implying asceticism and 'adi' means 'foot' signifying pilgrimage. Taken together the significance of the word is very clear. The devotee takes a vow to live the life of an ascetic for a particular period and then, as the culmination, travels to the temple of Lord Muruga by foot, bearing that symbol of purity - the Kavadi. Devotees carry different varieties of ‘Kavadi' like flower, milk, paneer etc. Traditionally, however, the devotee carries on his shoulders a semi-circular decorated canopy supported by a wooden rod to the temple of Lord Muruga, where special prayers are offered. This semi-circular object, called the Kavadi, signifies that the devotee has observed a term of strict abstinence in order to undertake the pilgrimage to the temple. The bearer of the Kavadi therefore earns respect all around.