In Tibetan Buddhism, OM MANI PADME HUM is the most adored mantra.
Tantrism in Tibetan Buddhism is respecting it as Fundamental mantra of the secret Lotus section, ie, the true precept of Avalokitesvara, which have it named by the Six Syllable Mantra.
OM MANI PADME HUM is written, drawn or carved in the building canopies Fangde, the ceiling, the doorframe, the religious apparatus, the rock or the slate most in Sanskrit or Tibetan Letters (In Mongolian areas, Monasteries also write it in Phags-pa Letters).
From literal interpretation of OM MANI PADME HUM, it means “Yidbzhin NorBu, Lotus!” Is it just a interjectional sentence, or an unfinished Buddhist scripture, or a compliment to Avalokitesvara, or a feeling to envision the happiness.
"OM" is the combination of the Sanskrit letters "a," "u," and "m." These three letters represent the enlightened body, speech, and mind of the Buddha. Our body, speech, and mind will be transformed into these when we are enlightened. The path to transform our body, speech, and mind into their enlightened counterparts is the practice of great compassion. Ordinary compassion is limited, but great compassion is unlimited and unconditioned. A mother may have deep compassion to her children, but she probably does not have great wisdom. Compassion and wisdom must be combined to reach enlightenment. That is the Mahayana path to enlightenment.
"MANI" means jewel. According to legend, there is a wish fulfilling jewel which will grant the wishes of its owner. It represents compassion. Compassion is like a wish fulfilling jewel, because it grants peace of mind.
"PADME" means lotus flower. It represents wisdom, the antidote to confusion. When you don't have wisdom, you talk and argue a lot. With wisdom this ceases. A lotus grows in the dirty water but remains unstained. It symbolizes how wisdom transcends confusion. A lotus has many petals and wisdom has many aspects.
"HUM" is the union of wisdom and compassion. We need to combine both to achieve enlightenment. The syllable "hrih" represents Avalokiteshvara's mind. If you know the meaning of the mantra, it becomes more meaningful.