Mantras are used in many religions and schools of thought, including Hinduism, Jainism, Buddhism, Sikhism and Transcendental Meditation. The use of mantras is thought by scholars to predate 1000 BC. There is even a suggestion that they may be older than language.
The most common use of mantras is to still the mind for meditation and some practitioners find this more helpful than simply focusing on the breath. The mantra may be chanted as many times as the student wishes. Some practitioners use mala beads to help them count and chant their mantra 108 times. This practice is known as japa or mantra japa. It may be performed in personal prayer, meditation or group prayer sessions.
It is believed that there are about 70 million mantras. Each mantra has its own sound and vibration, so when you chant it, you begin to vibrate within the frequency of that mantra. Some say that the vibrational power of each specific mantra is the power of the deity that presides over it. It is also said that the vibrations of the mantra can have healing effects, penetrating into the cells of the body and filling them with divine energy and strength.