1. Om (Aum) – the most important Hindu symbol, often used as the emblem of Hinduism. The eternal, mystical syllable; the syllable that stands for whole universe. It is pronounced with a nasalized ending, halfway between M and N. The letters comprise a triangle that physically delineate all the possibilities of sound. This sacred word encompasses in itself the whole universe, the past, the present and the future and goes beyond the periphery of Time itself. Beyond the symbol of the Brahman or the Universal Soul, it is the very essence of all that is sacred in Hindu thought. It is used at the beginning of meditation, at the beginning and at the end of a prayer, during the practice of Yoga, in fact at all times when the thought of the Brahman pervades one’s being.

2. Hands in prayer – Namaskar. Namaskar is the most popular form of greeting in India. It is a general salutation and is used as a welcome as also a farewell. Namaskar also means ‘I bow to thee’. The palms are placed together and raised to touch the forehead, the site of the Third Eye. Together, the hands symbolize the One Mind, or the self meeting the self, the right hand representing the holy, or higher nature, and the left, the worldly, or lower nature. Another term used for this greeting is namaste. Namaste may have originated in the ancient times as a showing of hands to prove that no arms were being carried.
 

3. Lotus (padma) – symbol of purity/transcendence. Growing out of the mud, it is beautiful, and though resting on water, it does not touch it. The lotus unfolds itself into a beautiful flower. Hence it is taken as the symbol of the universe coming out of the Sun. It rises from the navel of Vishnu, and is the seat of Brahma the Creator, hence the sacredness associated with it. It symbolizes self creation. Psychic centers in the body associated with the rising of the Kundalini power are pictured like lotuses. The padma or lotus pedestal is indicative of divinity and a number of deities are shown standing or sitting on it.
 

4. Conchshell – used during arati: one of the four symbols of Vishnu. The others are the lotus, club and disc.
 

5. Swastika – The word ‘Swasti’ means auspicious, benevolent, a good deed or good wishes. The Swastika is considered auspicious and is painted on the doors of houses in India to ward off evil spirits. Its origin goes back to the Vedic times (4500-2500 B.C.), maybe even earlier. Seals with the Swastika symbol have been found at excavation sites in Harappa which date back to about 200 years. The Swastika is in the form of a Greek cross with the ends of the arms bent at right angles. The right-handed Swastika moves in the clockwise direction and the left-handed in the counter-clockwise direction. The latter is considered an evil omen and generally never used.

The Swastika is said to represent the Sun or Lord Vishnu. In the Puranas it has been described as the ‘Sudarshana Chakra’ or wheel of Vishnu and also symbolizes the constant changes in the universe. The Swastika has also been associated with the Sun (the arms representing the sun’s rays) and also with Ganesha, the pathfinder whose image is often found at the crossroads.

In the ‘Siddhanta Saar’ the hub of  the Swastika has been described as the navel of Vishnu and the four lines as the four faces and four arms of Brahma. The Swastika is considered as a tantric symbol and is drawn in various religious festivals and auspicious occasions. During Diwali, the festival of lights, and the financial year-end for the Hindu businessmen, new account books are opened and decorated with the Swastika symbol and the words ‘Shubh-Labh’ (meaning ‘Auspicious Profit’) next to it. Prayers are also held so that the goddess of wealth, Lakshmi, will be benevolent.

6. Trident (trishul) – the symbol of Shiva; often carried by Shaivite sannyasis (renunciates).

7. Kalasha – coconut circled by mango leaves on a pot. Often used in rituals such as the fire sacrifice.

8. Cow – symbol of purity, motherhood and ahimsa (non-violence). The cow is sacred to the Hindus, a fact that puzzles the foreigner who finds numerous animals wandering the streets of the towns and cities, muzzling at fruit and vegetable stalls and sometimes obstructing traffic. For the early migrants the cow was an indispensable member of the family. As agriculture was the occupation of the migrants, the cow provided them with milk and its byproducts and also necessities of life such as fuel, manure for the farmer, etc. During this time the Aryans prayed to their numerous gods through ‘yagna’. This was initially a simple way of private worship but became public in character and consisted of invoking the fire-god, ‘Agni’, by ritually kindling sacred wood on an altar, and keeping the fire alive by constantly feeding it with melted butter. It was through the instrumentality of ‘Agni’ (fire) that the offering of milk-pudding and a drink of milk, curds and honey (madhupeya) was conveyed to one’s chosen gods. Thus the cow supplied the major requirements of the yagna and this association soon made it sacred.

Later on animal sacrifices waned as gradually the Hindus veered toward vegetarianism due to the influence of early Jainism and Buddhism, specially on the Brahmins and Vaishyas. Gradually the cow came to be known as ‘Gaumata’ (cow the Mother) and ‘Aditi’ (mother of gods). The rise of Vaishnavism amongst the prosperous middle and lower castes (expressed in the figure of the cowherd god Krishna) helped consolidate the importance and the religious glorification of the cow. Some of the other factors which resulted in its sanctity were; its figurative usage in Vedic literature which later was taken literally; prohibitions against killing a Brahmin’s (priest’s) cow and lastly, the symbol of cow protection as an affirmation of religious solidarity against Muslim invaders.

9. Lotus feet (of guru or deity) – touching the feet of superiors shows an attitude of submission and service.

10. Dipa/lamp – symbol of light.

Source- Hinduism: An Introduction & Hinduism.com