Sentience is the capacity for basic consciousness -- the ability to feel or perceive, not necessarily including the faculty of self-awareness. The word sentient is often confused with the word sapient, which can connotate knowledge, higher consciousness, or apperception. The root of the confusion is that the word 'conscious' has a number of different meanings in English. (One can easily distinguish the two by looking at their Latin roots: sentire, 'to feel,' and sapere, essentially 'to know.')
In the philosophy of animal rights sentience is commonly seen as the ability to experience suffering. The Eighteenth Century philosopher Jeremy Bentham raised the issue of animal suffering in An Introduction to the Principles of Morals and Legislation: "The French have already discovered that the blackness of the skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor... What else is it that should trace the insuperable line? Is it the faculty of reason, or, perhaps, the faculty of discourse? But a full-grown horse or dog is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day, or a week, or even a month, old. But suppose the case were otherwise, what would it avail? the question is not, Can they reason? nor, Can they talk? but, Can they suffer?"
The issue of sentience also frequently arises in science fiction stories describing robots or computers with artificial intelligence. Some science fiction uses the term sentience to describe a species with human-like intelligence, but a more appropriate term is sapience.
Eastern religions including Buddhism and Jainism recognize nonhuman beings as sentient beings. In Jainism, this is closely related to the concept of ahimsa, nonviolence toward other beings. In Mahayana Buddhism, including Zen and Tibetan Buddhism, the concept is related to the Bodhisattva, an enlightened being devoted to the liberation of others. The first vow of a Bodhisattva states: "Sentient beings are numberless; I vow to free them."