Gratitude, thankfulness, or gratefulness is the proper, fitting or called-for response to benefits or beneficence from a benefactor. The experience of gratitude has historically been a focus of several world religions. It has also been a topic of interest to ancient, medieval and modern philosophers, and continues to engage contemporary western philosophers today. The systematic study of gratitude within psychology only began around the year 2000, possibly because psychology has traditionally been focused more on understanding distress rather than understanding positive emotions. The study of gratitude within psychology has focused on the understanding of the short term experience of the emotion of gratitude (state gratitude), individual differences in how frequently people feel gratitude (trait gratitude), and the relationship between these two aspects.
Gratitude is not the same as indebtedness. While both emotions occur following help, indebtedness occurs when a person perceives that they are under an obligation to make some repayment of compensation for the aid. The emotions lead to different actions; indebtedness can motivate the recipient of the aid to avoid the person who has helped them, whereas gratitude can motivate the recipient to seek out their benefactor and to improve their relationship with them.
Gratitude may also serve to reinforce future prosocial behavior in benefactors. For example, one experiment found that customers of a jewelry store who were called and thanked showed a subsequent 70% increase in purchases. In comparison, customers who were called and told about a sale showed only a 30% increase in purchases, and customers who were not called at all did not show an increase. In another study, regular patrons of a restaurant gave bigger tips when servers wrote "Thank you" on their checks.
The link between spirituality and gratitude has recently become a popular subject of study. While these two characteristics are certainly not dependent on each other, studies have found that spirituality is capable of enhancing a person’s ability to be grateful and therefore, those who regularly attend religious services or engage in religious activities are more likely to have a greater sense of gratitude in all areas of life. Gratitude is viewed as a prized human propensity in the Christian, Buddhist, Muslim, Jewish, Baha'i, and Hindu traditions. Worship with gratitude to God is a common theme in such religions and therefore, the concept of gratitude permeates religious texts, teachings, and traditions. For this reason, it is one of the most common emotions that religions aim to provoke and maintain in followers and is regarded as a universal religious sentiment.