This document discusses the concept of gratitude from several perspectives. It defines gratitude as stemming from recognizing a positive outcome from another person's intentional and costly behavior that benefits the recipient. Gratitude is seen as a virtue across many cultures and religions. Studies have shown gratitude can increase life satisfaction and well-being. Expressing appreciation was found to shift heart rhythm coherence from the frustrated right frontal lobe to the positive emotion center in the left lobe. More research is still needed but expressing gratitude seems to have psychological benefits.