DasAvatAram is the story of Bhagwan’s ten incarnations which happened over a period of four Yugas. Dasa means 10 and avatAram can be translated as incarnation.
When we say ten, it does not mean that HE only incarnated ten times to save all creation. Infact his incarnations are innumerable. Out of those, BhAgawatam talks about 25 incarnations, the Rishis and the Acharyas selected the most important ones and gave it to us as dasAvatAram.
First let us see what the word avatar itself means. Avatar means, to descend or to make appearance. In sanskrit when we say, VrikshAt avararati, it means getting down from a tree. Bhagwan descends from his abode Vaikunta, to this world for our sake.
Why should Bhagwan incarnate? Why should he be born? Great Acharyas say that, HE takes birth on earth to re-establish Dharma and to save us from taking birth again and again and be caught in this whirlpool of Life and Death.
Again, why should HE himself descend? Why doesn’t he send one of the NityaSooris ( the immortals who are always with Him whose sole purpose is service to the Lord). For instance, there was a King, who went on a joy ride on his luxurious ship along with his queen and his baby, He is accompanied by his chief of army and a few trustworthy soldiers. The jubilant queen was holding the baby in her arms and was enjoying the setting sun. Suddenly due to a high tide, the ship shook violently. The queen lost her balance and the baby fell out of the ship into the rough sea. Now at this moment, will the King, calmly, without getting up from his comfortable seat, just give orders to his chief to jump and save the baby? Or will he dive into the sea himself , to save his baby? Certainly, the moment he hears the cries, the king will himself jump into the water without a second thought and save the baby. Because at this moment he is acting as a father, rather than a king. Bhagwan descends in the same way, to protect us as we are all His children.
In Bhagawad Gita , Krishna says Sambhavami Yuge Yuge !!! He promises to descend again and again. Whenever the righteousness fades and evil manifests itself in everything Lord Vishnu descends to the earth, to protect the good , to destroy evil and to re-establish Dharma. As seen earlier, ten such incarnations or avatArs are the celebrated ones. They are , Matsya ( the Fish form), Kurma ( the Tortoise form), Varaha ( the Wild Boar form), Narasimha ( the Man-Lion form), Vamana ( the Short Bramhan form), Parasurama ( the Rishi who wields an Axe), Rama (Son ofKing Dasaratha), Balarama ( the elder brother of Krishna), Krishna ( the one with a Flute and Peacock feather, who was instrumental of the Mahabharatha) and lastly Kalki ( Warrior form who rides on a White Horse).
यदा यदा हि धर्मस्य ग्लानिर्भवति भारत ।
अभ्युत्थानमधर्मस्य तदात्मानं सृजाम्यहम् ॥४-७॥
परित्राणाय साधूनां विनाशाय च दुष्कृताम् ।
धर्मसंस्थापनार्थाय सम्भवामि युगे युगे ॥४-८॥
Whenever there is decay of righteousness, O Bharata,
And there is exaltation of unrighteousness, then I Myself come forth ;
For the protection of the good, for the destruction of evil-doers,
For the sake of firmly establishing righteousness, I am born from age to age.