What is behavioural economics?

Behavioural economics is a branch of economics that concentrates on explaining the economic decisions people make in practice, especially when these conflict with what conventional economic theory predicts they will do.
According to psychologists, people are mainly influenced by a fear of feeling regret and will often forgo benefits even to avoid only a small risk of feeling they have failed.
This economic category is primarily focussing upon the human emotions to counter things which could emotionally effect them in decision making process.

Behavioral economics” improves the realism of the psychological assumptions underlying economic theory, promising to reunify psychology and economics in the process. Reunification should lead to better predictions about economic behavior and better policy prescriptions. Behavioral economics is one of the hottest ideas in public policy. Behavioral economics applies psychological insights into human behavior to investigate how people make economic decisions under various conditions of constraint

Because economics is the science of how resources are allocated by individuals and by collective institutions like firms and markets, the psychology of individual behavior should underlie and inform economics, much as physics informs chemistry; archaeology informs anthropology; or neuroscience informs cognitive psychology. However, economists routinely and proudly use models that are grossly inconsistent with findings from psychology. A recent approach, “behavioral economics,” seeks to use psychology to inform economics, while maintaining the emphases on mathematical structure and explanation of field data that distinguish economics from other social sciences.