The Sūtra on Impermanence (1)

All conditioned phenomena are impermanent; all defilements are suffering; all phenomena are without self; nirvāṇa is peace.

Definition from the 84000 Glossary of Terms:

One of the first Buddhist monasteries, located in a park outside Śrāvastī, the capital of the ancient kingdom of Kośala in northern India. This park was originally owned by Prince Jeta, hence the name Jetavana, meaning Jeta’s grove. The wealthy merchant Anāthapiṇḍada, wishing to offer it to the Buddha, sought to buy it from him, but the prince, not wishing to sell, said he would only do so if Anāthapiṇḍada covered the entire property with gold coins. Anāthapiṇḍada agreed, and managed to cover all of the park except the entrance, hence the name Anāthapiṇḍadasyārāmaḥ, meaning Anāthapiṇḍada’s park. The place is usually referred to in the sūtras as “Jetavana, Anāthapiṇḍada’s park,” and according to the Saṃghabhedavastu the Buddha used Prince Jeta’s name in first place because that was Prince Jeta’s own unspoken wish while Anāthapiṇḍada was offering the park. Inspired by the occasion and the Buddha’s use of his name, Prince Jeta then offered the rest of the property and had an entrance gate built. The Buddha specifically instructed those who recite the sūtras to use Prince Jeta’s name in first place to commemorate the mutual effort of both benefactors.

Anāthapiṇḍada built residences for the monks, to house them during the monsoon season, thus creating the first Buddhist monastery. It was one of the Buddha’s main residences, where he spent around nineteen rainy season retreats, and it was therefore the setting for many of the Buddha’s discourses and events. According to the travel accounts of Chinese monks, it was still in use as a Buddhist monastery in the early fifth century ᴄᴇ, but by the sixth century it had been reduced to ruins.

Definition from the 84000 Glossary of Terms:

The first of the four truths of the noble ones. The term “suffering” includes all essentially unsatisfactory experiences of life in cyclic existence, whether physical or mental. These comprise (1) the suffering of suffering, i.e., the physical sensations and mental experiences that are self-evident as suffering and toward which spontaneous feelings of aversion arise; (2) the suffering of change, i.e., all experiences that are normally recognized as pleasant and desirable, but which are nonetheless suffering in that persistent indulgence in these always results in changing attitudes of dissatisfaction and boredom; and (3) the suffering of the pervasive conditioning underlying the round of birth, aging, and death.

Impermanence, suffering, and no-self. They are called in Pāli tilakkhaṇa, the “three characteristics,” a term that has no direct equivalent in the Sanskrit or Tibetan literature; in Tibetan, these three factors are usually called the “three seals of the Buddha’s teaching” in parallel to the “four seals of the Buddha’s teaching,” q.v.