Meditation

Meditation is generally an internal, personal practice and done without any external involvement.
Meditation often involves invoking or cultivating a feeling or internal state, such as compassion, or attending to a specific focal point.
There are dozens or more specific styles of meditation practice. People may mean different things when they use the word, 'meditation'. Meditation has been practiced since antiquity as a component of numerous religious traditions, especially in monastic settings.

Om, not much.

OM is not referred for the all thing of MEDITATION .

AUM is the most scared symbol in the HINDU dharma. Aum (OM) is the sound of the infinite.Aum is said to be the essence of all mantras, the highest of all matras or divine word (shabda), brahman (ultimate reality) itself. Aum is said to be the essence of the Vedas.

By sound and form, AUM symbolizes the infinite Brahman (ultimate reality) and the entire universe.

In the Hindu mythology the word AUM stands for.

A stands for Creation

U stands for Preservation

M stands for Destruction or dissolution

This is representative of the Trinity of God in Hindu dharma (Brahma, Vishnu and Shiva)

The three portions of AUM relate to the states of waking, dream and deep sleep and the three gunas (rajas, satva, tamas)

The three letters also indicates three planes of existence, heaven (swarga), earth (martya) and netherworld (patala)

All the words produced by the human vocal organ can be represented by AUM. A is produced by the throat, U & M by the lips

In the Vedas, AUM is the sound of the Sun, the sound of Light. It is the sound of assent (affirmation) and ascent (it has an upwards movement and uplifts the soul, as the sound of the divine eagle or falcon.