Vishnu is the all-pervasive Lord who expands into everything. He is the maintainer of the universe and the complete cosmic creation. He is called Vishnu because he overcomes all. he represents sattva-guna, or the mode of goodness by which everything is sustained. He is also called Narayana, which means the shelter, resting place or ultimate goal of all living entities. It also means the one whose abode is the causal waters, and one who lives in the hearts of all living beings. It is this sattva nature which gives the living beings the tendency to grow toward a higher truth, the light, a more cohesive and intense reality. In this sense, Lord Vishnu is also called Hari, or one who removes the darkness of illusion. This illusion ultimately means the idea that the living beings live separate from, or without connection to, the Lord.
Vishnu’s earthly incarnations have many avatars. His ten avatars are 'Matsyavatara', 'Koorma', 'Varaaha', 'Narasimha', 'Vamana', 'Parasurama', 'Lord Rama', 'Lord Balarama', 'Lord Krishna', and the yet to appear 10th incarnation called the 'Kalki' avatar. Some sources consider 'Buddha' as one of the avatars of Vishnu. This is a much later addition done at a time when the concept of 'Dashavatara' was already developed.
Sankha, Chakra, Gada, Padma
On one of the backhands he holds the milky white conch shell or ‘Sankha’ that spreads the primordial sound of Om, and on the other a discuss or ‘Chakra’ - a reminder of the cycle of time - which is also a lethal weapon that he uses against blasphemy. It is the famous Sudarshana Chakra that is seen whirling on his index finger. The other hands hold a lotus or ‘Padma’, which stands for a glorious existence, and a mace or ‘Gada’ that indicates punishment for indiscipline.