Dasavatharam of Lord Vishnu

Das means Ten. Avatar means incarnation. Dasavathar means Ten incarnations of Lord Vishnu.As per Hindu mythology, Lord Brahma is responsible for creation, Lord Vishnu is responsible of saving (upkeep) and Lord Shiva is responsible of extermination.

Of the ten universally recognized avatars, nine have already appeared whereas the tenth is yet to appear. These ten avatars are also known by the name of Dasha Avatar of Vishnu. 

1.Matsya Avatar - Lord Vishnu in the form of Fish

The first avatar, Matsya, was taken by Lord Vishnu at the end of the Satyuga (last age), when a flood destroyed the world. In this avatar he saved humanity and the sacred Veda text from the 

flood.

2.Kurma Avatar - Lord Vishnu in the form of Turtle

It is also appeared at the end of satya yuga. When the devas and asuras were churning the Ocean of milk in order to get amrita,He helped devas to obtain the amrut (nectar) of immortality which was also sought after by the Asuras (demons). 

3.Varaha Avatar - Lord Vishnu in the form of Boar

In Satya yuga when Bhoomi Devi (Earth Mother) sank to the bottom of the ocean. Vishnu, in the form of varaha, dived into the ocean and raised the goddess out of the ocean, supported by his two tusks. 

4.Narsimha Avatar - Lord Vishnu in the form of Half - Man and Half - Lion 

This avatar takes place in satya yuga to kill the demon king Hiranyakashipu.Narsimha is the only avatar which was Hybrid in form being half human and half animal. 

5.Vamana Avatar - Lord Vishnu in the form of a Dwarf 

This avatar appeared in Treta Yuga in order to destroy Bali, the king of demons.

6.Parshurama Avatar - Lord Vishnu in the form of a Brahmin

In Treta yuga whe kings are harassing people and saints in the forest, he appeared in the form of parshurama and destroyed all the kings.

7.Rama Avatar - Lord Vishnu in the form of the King

 It is one of the most popular avatar of Lord Vishnu.In Treta Yuga he appeare as king of ayodhya,to rescue Sita with his loyal servant Hanuman and his brother, Lakshmana, and killed the demon Ravana. 

8.Krishna Avatar - Lord Vishnu in the form of a Cowherd's Boy

It is also the popular avatar of lord Vishnu.This avatar was occured in Dwapara Yuga.Lord Krishna conveyed the message of love and humanity to the world. Krishna told the epic poem Bhagavad Gita to the warrior Arjuna ,in which he acclaimed : ''Whenever Dharma, or the situation of law and order, is endangered on this world, I incarnate onto this world to re establish Dharma, law and order, and to protect the Sadhus or saints and to destroy the evil elements of the society.'' 

9.Buddha Avatar - Lord Vishnu in the Form of Buddha

Mahavira Buddha, appeared in the Kalyuga, to teach the lesson of following a middle path in life. ''Buddha'' means 'the enlightened one'. He taught that all sorrow comes from attachments and desires, so it's better to curb all attachments in order to remain happy. 

10.Kalki Avatar

The Kalki avatar   is yet to appear on the earth. And it is expected to appear at the end of Kali Yuga, the time period in which we currently exist, which will end in the year 428899 CE.