What is the Consumer Surplus and how may this Happen?

-This is when the Consumer buys a Good for Less [say $2] than what they were Expecting [$5] -The Consumer Surplus above would be $3 - That's the Difference between the Price that a Consumer is Willing to Pay, and the Price they Actually Pay [Equilibrium Price] -This may happen as Consumers have simply Different Thought Engines, Preferences, Incomes and Views.