Everybody knows about dashavatar of lord vishnu ,but the reason behind of this avatar (incarnation) still unknown for few, here is dashavatar of prabhu:

1- matsya 2- kurma (tortoise) 3- varah 4 - narsimha 5- vamana 6- parshurama 7- Sri Ram 8- prabhu krishna 9- buddha 10- kalki

In satyuga prabhu incarnation happend 4 times
1- matsya avtar 2- kurma avatar (tortoise) 3 - varaha avatar 4- narsimha avatar

In Treta yuga prabhu incarnation happend 3 times which is Vamana,Parshurama , Sri Rama

In Dwapar Lord Krishna came

In kaliyuga (present yuga) prabhu came in as a gautam buddha last avatar of prabhu is yet to be happn which is kalki

So from tomm i ll write about each avatar

Om namo bhagwate vasudevaya