Tipping is a multi-billion-dollar phenomenon that standard economic models find hard to explain. I discuss several aspects of tipping and divide tipping to six different categories: reward-tipping, price- tipping, tipping-in-advance, bribery-tipping, holiday-tipping and gift- tipping, and...

The article presents a theory that I denote “Relative Thinking Theory,” which claims that people consider relative differences and not only absolute differences when making various economics decisions, even in those cases where the rational model dictates that people should consider only...