Imagine you are shopping for a new phone. A perfectly logical shopper would weigh every spec, read every review, and pick the one that gives the most value for the money. But real people walk into a store, get drawn to a shiny display, and buy the one that feels right — even if it costs more. Financial decisions are full of the same human quirks, and that is exactly what this chapter is about. We are leaving the tidy world of perfectly rational investors behind and stepping into the messier, more realistic landscape of behavioral finance.