The main elements of Hinduism are the Sanskaras, which are the stepping-stones for a pure and righteous life. The basic element for achieving this is through Pooja. POOJA Pooja should be done facing the east, though it is not a requirement. This facing towards the east is called Surya Namaskar and the inherent benefit is that the energy of the sun infuses its divine attributes into the worshipper. Pooja can be performed for various reasons and to various deities: For example to mother Saraswati the Goddess of learning, for knowledge or to Ganesha for understanding. Panchopachar or Pooja appeals to all five senses.(seeing, hearing, speaking, smelling, and tasting) Thus seeing the deity, idol or murti, hearing the chants and bell, recitation of a mantra, smelling the agarbatti and tasting the blessed prasad. DARSHAN The most important part of the pooja is the mutual visual exchange between the god and the devotee, which is called darshan. This visual communication is believed to bring blessings to the devotee. OM We often hear people saying “Ooooooom” but what does that mean? It is a Hindu symbol and sacred syllable, which represents Brahman, the absolute. Om includes every sound in the universe; it is the past, present, and the future. Om stands at the beginning of every hymn, recitation of text, and every religious action. MANTRA Hinduism is encircled by the importance of mantras. According to the most orthodox rules, conception of a child must be accompanied by the recitation of mantras. Mantras are recited during birth, marriage, temple visits, and all other rituals and result in inner purification. One who recites mantras also gains concentration and stability of the mind.
Basically its 'AUM' but many times i have seen people writing 'Om'. Actually the correct sound is AUM but since when we say it it comes out as OM. In ancient times the great maharishis and saints discovered sacred geometry symbols and representations known as Yantras. Each and every sound when you recite Om turns out to be as , AUUMMM....So the mantras and their sound are also represented in the form of Shree yantra which is available at any spiritual store. Even they you tube link says the same thing. ~Hari Om