Incarnations of Lord Vishnu

 Matsya, Kurma, Varha, Narshimah, Vamana, Parshuram, Kasrishna, Rama, Budha, kalki are vishnu's incarnations (Dashavatars)

• MATSYA  

Vishnu takes avatar in the form of Fish to save Manav or Childerns of manav from the Paralya.

• KURMA    

kurma is Giant Tortoise.Vishnu takes this  avtar during Samundra Manthan(Churning  the ocean) to bear the weight of mountain.

• VARAHA    
  
    

Vishnu appears as Boar to defeat Asura  Hiranyaksha. Demon Hiranyaksha had taken the mother Earth  into the bottom of Cosmic Ocean(According to Hindu mythology) . varaha won this battle & carried the earth between his Tusk and resored in the Universe.

• NARASIMA 
  

Narasima Is in  the form of Part Man & Part of Lion.The Rakshaa  HIRANYAKASHIPU was gained special powers(Vardana) by God of Creation  BRAHMA by which he couldn't be Killed by Man or Animal,by God or Demon,Inside or Outside,during Day or Night. That's why VISHNU adapts Avatar i.e neither Man not Animal then he killed the Demon at the courtyard with his claws when he lay on his thighs.

• VAMANA (dwarf)

Vishnu takes avtar as VAMANA to defeat Asura king MAHABALI creativly. VAMANA went to BALI and promise him for wetever he asked.Vamana demand for three paces of land & BALI agreed and then Vamana increase his size.First he steeped over Heaven & second in netherworld . Bali feels Vamana was vishnu Avatar.Then King Bali offered his head as a Third place.Dwarf  place his foot on Bali';s  head.