What is consumer surplus? Why would policy makers be interested in consumer surplus?

What will be an ideal response?

Consumer surplus is the difference between what a consumer is willing to pay for a product and what she actually pays for the product. Since consumer surplus measures the benefit that consumers receive from a good as they themselves perceive it, it serves as a good measure of economic well-being. Thus, if policy makers care about consumer preferences, they could use this measure to make normative judgments about market outcomes.