The term dhamma comes from the Sanskrit word dharma, which meaning "holy obligation." Thus, dhamma means "that which holds us to our life vows" or "the path." Dhamma is one of the principal themes in the Buddha's teachings. It can be translated as "law," "system," "method," "teachings," or "doctrine." The Pali word for doctrine is Dīgha, so Buddhism is sometimes called the Dīgha Nikāya (Long Discourse School). Dhamma is an important concept for Buddhists. They believe that everything in existence can be divided into two categories: what exists by virtue of its relationship to the soul (atman), and what exists due to other causes. The correct understanding of reality leads to liberation (moksha) from saṃsāra, the cycle of death and rebirth. At any given moment, you have a choice between acting according to universal law or following your own desires. If you choose to act according to law, then it's called karma yoga. If you choose to follow your own desires, then it's called rajayoga.