The Buddha’s teaching called paticca-samuppada, usually translated as dependent origination, is fundamental to the Dhamma awakened to by the Buddha on the night of his Enlightenment. The Buddha is recorded to have said:
One who sees Dependent Origination, sees the Dhamma.
One who sees the Dhamma, sees Dependent Origination. MN 28
This wheel publication offers an overview of paticca-samuppada.