Lord Vishnu's preserving, protecting powers have been manifested to the world in a variety of forms, called Avatars, in which one or more of his divine attributes were embodied in the shape of a human being or an animal or a human-animal combined form, possessing great and sometimes supernatural powers. All these Avatars of Vishnu appeared in the world either to correct some great evil or to effect some great good on earth. These avatars are ten in number, however, the Bhag wad Purana increases them to twenty two and adds further that are innumerable.

Of the ten universally recognized avatars, nine have already manifested whereas the tenth is yet to appear.

It is important to note that the all the Avatars are earthly form of Lord Vishnu , who himself is eternal, unchangeable and immutable.

Parashurama shows the man of power, Rama the Divine warrior and protector, Krishna the Divine lover, Buddha the Divine sage, and Kalki the completer and saviour . In this scheme we see the idea of the evolution of the soul from the animal re alms to perfect spiritual knowledge.

Before the latest creation of the present universe, the four Vedas (the holy books delivered from the mouth of the Supreme-God) remained drowned in the waters. It was necessary to get hold of them to instruct Brahma about the work of creation. Vishnu was therefore appointed to bring up the Vedas from the deep. He took the form of a fish (matsya), descended into the waters and brought up these sacred books.

In Kurma avatar, Lord Vishnu assumed the form of a tortoise and took the newly created earth on his back in order to render stability to the trembling globe. It is believed that even to this day the earth is supported on the back of this tortoise.

In periodical destruction of the world, once the earth sunk into the deep waters. Lord Vishnu, the great preserver, taking the form of a boar (Varaha), descended into the waters and drew up the earth with the help of his tusks.

This special form was adopted by Lord Vishnu to kill a demoniac ruler Hiranyakashyap, who had pleased the Lord Brahma with his religious offerings.

Lord Brahma had given him the blessings that no known man or animal born in the natural process could kill him, that he could not die in the day or in the night, on earth or in heavens, either by fire, water or by any weapon.

It was to kill such a tyrant and to remove him from the earth that Lord Vishnu assumed the form of Narasingh which was neither man nor animal, came out of a broken pillar, laid hold of the demon king by its teeth, put him up on his thighs and tore him up in the middle by his claws. It was evening time (twilight) - neither day nor night.

The fourth lineal descendant of Hiranyakashyap, named Bali, through his devotion and penance defeated Indra, the god of firmament, humbled other gods and extended his authority over the three worlds.

All the gods appealed to Lord Vishnu for protection and He became manifest in His Dwarf Avatar of Vaman for the purpose of restraining Bali.

Once when this king was making a great religious offering, Lord Vishnu in the form of Vaman appeared before him in the company of other brahmins. Bali was extremely pleased to see a holy man with such a diminutive form and promised to give him whatever he should ask. Lord Vishnu asked only for as much land as he could measure by three steps. Bali laughingly agreed to grant the boon of three steps.

Lord Vishnu as dwarf stepped over heaven in first stride and earth in the second stride. Then out of respect to Bali's kindness and his grandfather Prahlad's great virtues, Lord Vishnu stopped short and left him in pathal, the subterranean region. Bali's capital was Mahabalipuram.

Parsu is the name of an axe-like weapon adopted by this incarnation.

Parasuram was a brahmin who manifested himself at the close of the satya-yug. This appearance was for the purpose of defeating the tyranny of the power-drunk kshatriyas.

When the kshatriya kings of the earth and their ministers became very corrupt and tyrannical, the goddess Prithvi (Mother Earth) went to Lord Vishnu and prayed for relief. Lord Vishnu answered the prayer and appeared on the earth as a descendant of the great sage Brigu. Parasuram avenged the gruesome murder of his father by a kshatriya king and freed the earth of oppression perpetrated by the rulers by clearing the earth of kshatriyas

Lord Rama is one of the most commonly adored gods of Hindus and is known as an ideal man and hero of the epic Ramayana.

He is always holding a bow and arrow indicating his readiness to destroy evils. He is also called "Shri Rama". More commonly he is pictured in a family style, (Ram Parivar) with his wife Sita, brother Lakshman and devotee Hanuman who is sitting near Lord Rama's feet.

Because of his great Godly power, Lord Krishna is another of the most commonly worshipped deities in the Hindu faith. He is considered to be the eighth avatar of Lord Vishnu. Shree Krishna delivered Bhagwad Gita on battlefield to Arjun.

He, like Lord Rama, is also known for his bravery in destroying evil powers throughout his life. The Lord is usually depictted as play ing the flute (murali), indicating spread of the melody of love to people.

He is also shown with his childhood devotee Radha. The Lord is usually remembered and worshipped as Radha-Krishna. The pair symbolizes the eternal love between people and god.

Lord Krishna is also shown with his pet cow, his childhood favorite. Lord Krishna performed many divine sports (leela) as a child.

With the departure of Lord Krihsna (Krishna Avatar), the age of Kali set in, in this age, the true devotion to vedas was replaced by empty rituals.  To enlighten the world in such times, Lord Vishnu descended the earth as Buddha, the enlightened one.

Lord Buddha was born to Mayadevi, the wife of Sakya King Shuddhodana, in the Lumbini forest, and named Siddhartha.

Buddha advocated the Middle Path, in which he offered a balanced, harmonious way of life, steering between two extremes of self-indulgence and total abstinence. Buddhism rests upon four Noble Truths:

• Suffering is universal,
• It is caused by desire and yearning
• Suffering can be prevented and overcome and
• Eradication of desires can lead to removal of suffering.

To prevent suffering one has to conquer craving and desire and this conquest leads to the attainment of nirvana or complete enlightenment

The tenth and the last avatar of Vishnu, Kalki, is yet to appear. Kalki will appear at the end of the Kalyuga. This avatar will appear seated on a white horse with a drawn sword blazing like a comet.

He shall come finally to destroy the wicked, to restart the new creation and to restore the purity of conduct in people's lives .