Repentance is a very important thing in learning Buddhism. We create bad karma every day from thought, speech and action. We may not be able to recognize that we have done them, but since we came to this world, we have already brought the karma of our past lives. And that's why repentance is so important in Buddhist daily practice.
Usually Buddhists do repentance by reciting repentance verse and bow to the Buddha and Bodhisattva. Actually, in Buddhism don't seek for forgiveness from Buddha or Bodhisattva only, they do seek repentance and vow to repent, and thus asking the Buddhas or Bodhisattvas to become witness of repentance. And since it's so important, this repentance practice in Buddhism should be done daily and continuously up till the moment of our death. Bad karma arises from our greed, hatred and ignorance. So, we vow not to repeat again and again.
Now, let's listen to this song of Repentance: