Kindness is a type of behavior marked by acts of generosity, consideration, rendering assistance, or concern for others, without expecting praise or reward in return.
Kindness is a topic of interest in philosophy, religion, and psychology. Kindness was one of the main topics in the Bible. In Book II of Rhetoric, Aristotle defines kindness as "helpfulness towards someone in need, not in return for anything, nor for the advantage of the helper himself, but for that of the person helped". Friedrich Nietzsche considered kindness and love to be the "most curative herbs and agents in human intercourse". Kindness is one of the Knightly Virtues. In Meher Baba's teachings, God is synonymous with kindness: "God is so kind that it is impossible to imagine His unbounded kindness!"
In English, the word kindness dates from approximately 1300, though the word's sense evolved to its current meanings in the late 1300s.
Over time, it has acted in part of a personality trait as a long tradition of generosity through human cultures and family-friendly benefits in the concept of hospitality.
Human mate choice studies suggest that both men and women value kindness in their prospective mates, along with intelligence, physical appearance, attractiveness, and age.
Studies at Yale University using games with babies concluded that kindness is inherent to human beings. There are similar studies about the root of empathy in infancy – with motor mirroring developing in the early months of life, and leading (optimally) to the concern shown by children for their peers in distress.
Barbara Taylor and Adam Phillips stressed the element of necessary realism in adult kindness, as well as the way "real kindness changes people in the doing of it, often in unpredictable ways".
Behaving kindly may improve a person's measurable well-being. Many studies have tried to test the hypothesis that doing something kind makes a person better off.