What it means
I bow to Ganapati, lord of the ganas. Gam is Ganesha's seed syllable. The ganas are Shiva's attendants, and more broadly every kind of group; Ganapati leads them all.
Where it comes from
The Ganapati Atharvashirsha explains how this seed syllable is formed, and the full mantra appears there too. In Maharashtra it's said before starting almost anything, at home or in business: a new car, a new house, an exam. Through the ten days of Ganesh Chaturthi you'll hear it in every pandal.
How to chant it
Offer durva grass and a modak to Ganesha, then chant on a mala. Saying it 21 times just before starting something is common too.
When: Wednesdays, Ganesh Chaturthi, and at any new beginning.
Try it now
The japa counter opens with this mantra selected and keeps count for you.
Questions people ask
An old story says that after Ganesha swallowed the demon Analasura his stomach burned, and durva grass cooled it. Since then durva has been his favourite offering.