The three marks, tilakkhaṇa, are anicca, impermanence; dukkha, unsatisfactoriness; and anattā, not-self. To see them directly in one’s own experience is the work of insight meditation. Some later Mahāyāna formulations, the “seals of the Dharma”, replace suffering with nirvāṇa as peace.
Three marks of existence
Impermanence, suffering and not-self: the characteristics of all conditioned things.
Also: tilakkhana