Mettā (Pāli: मेत्ता) or maitrī (Sanskrit) has been translated as "loving-kindness," "friendliness," "benevolence," "amity," "friendship," "good will," "kindness," "love," "sympathy," and "active interest in others." It is one of the ten pāramitās of the Theravāda school of Buddhism, and the first of the four Brahmavihāras. The mettā bhāvanā ("cultivation of mettā") is a popular form of meditation in Buddhism.
The object of mettā meditation is loving kindness (love without Upādāna, that is, attachment). Traditionally, the practice begins with the meditator cultivating loving kindness towards themselves, then their loved ones, friends, teachers, strangers, enemies, and finally towards all sentient beings. Commonly, it can be used as a greeting or closing to a letter or note.
Buddhists believe that those who cultivate mettā will be at ease because they see no need to harbour ill will or hostility. Buddhist teachers may even recommend meditation on mettā as an antidote to insomnia and nightmares. It is generally felt that those around a mettā-full person will feel more comfortable and happy too. Radiating mettā is thought to contribute to a world of love, peace and happiness.
Mettā meditation is considered a good way to calm down a distraught mind by people who consider it to be an antidote to anger. According to them, someone who has cultivated mettā will not be easily angered and can quickly subdue anger that arises, being more caring, more loving, and more likely to love unconditionally. Recent neurological studies have shown that compassion meditation can increase one's capabilities for empathy by changing activity in brain areas such as the temporal parietal juncture and the insula, and increase the subject's ability to understand the mental and emotional states of others as well as deal more effectively with external stressors.