An avatar, similar to the Christian concept of the incarnation of God, is different in two ways. Firstly, a god can incarnate in many places at the same time through "partial" avatars, called amshas, but the main from remains entirely “full". Secondly, the incarnations do not completely participate in the human sufferings and also lose the power and knowledge of their divine form.
The term 'Vatar' symbolizes the one who has descended. It means that he descended from his godly state to the human form. So, Avatar means the beings who descended from the Spiritual World to the Earth to establish Dharma, preserve the human race and promulgate Sastra. Thus, Avatar means the form who descends as a partially or fully-empowered incarnation of the Divine Mother, Adhiparasakthi.
An Avatar, also called a Saviour, is a person who rescues or saves mankind from deterioration. He saves the earth by his grace. Whenever virtue subsides and wickedness prevails, and whenever unrighteousness rises or Adharma starts, and whenever there is destruction and unrest in this world, our Divine Mother incarnates herself. Adhiparasakthi descends to this physical plane to establish the virtues of Dharmas and to save the good and destroy the evil. When she descends to the physical plane and takes a human form she is known as an avatar.
An avatar is also known as the Messenger of the Divine because the avatar transmits pure and unselfish love from the divine power to mankind. He gives a taste of the unadulterated sweet nectar of heavenly love to the souls scorched by the fire of worldliness and pain. The omnipotent Mother Adhiparasakthi, who is Bliss, Truth and Consciousness, bestows special grace and manifests herself as a common person during her Avatar life. In this period, the divine goddess acquires a human form and incarnates herself so as to set an example before us in this life. It is her speciality that, in spite of being omnipresent and boundless, she becomes a tiny human