All of these things are examples of doctrinal aspects of Hinduism.
Dharma is probably the most important ethical proponent of Hinduism.
Purification, usually with water, is thus a typical feature of most religious action. Avoidance of the impure--taking animal life, eating flesh, associating with dead things, or body fluids--is another feature of Hindu ritual and is important for repressing pollution.
Yet another material aspect of Hinduism are cows.
Aum, also written "Om" and called pranava, is the most important Hindu symbol. Its prolonged intonation is associated with the primeval sound through which the universe was created. It is thought to contain all things. It consists of three syllables — a-u-m — which are sounded progressively from the throat to the lips. The three sounds are considered to symbolise many items, but perhaps most importantly the three states of consciousness – waking, dreaming, and deep sleep. The entire symbol represents the fourth state, which is the awareness of one's own spiritual identity. Aum is the most important mula (root) mantra and is thus chanted at the beginning of many prayers, mantras, and rituals.