Some contracts - contracts in equity or equitable contracts - focus on aspects of the law that have to do with justice and fairness. They reinforce trust in the legal system itself and give people some basis that their obligations in general will be met even if the technical law does not permit the recovery. There are two main types of contracts in equity: based on promissory estoppel and on promissory restitution. Let me give you a simple example of a contract based on promissory estoppel. Your grandfather promises to pay for your law school education. Based on his promise you attend law school and get into thousands of dollars worth of debt to pay for your courses and books. After your grandfather passed away, the estate refuses to pay, arguing (and they are correct) that your grandfather made a gratuitous promise. This was a gift. Your grandfather didn't say, I'll pay for your law school if you'll represent me for the rest of my life for free. There was no bargain for exchange. There was no consideration. This was merely a gratuitous promise or gift promise, so it’s not enforceable at law, which requires consideration as an element of a contractually binding agreement. But it may be enforceable at equity. If you reasonably rely on your grandfather, trusting him that he would fulfill his promises. And if his promise reasonably should have induced you to take some action or forbearance. And now you have taken some action that has been to your detriment, r, we have a classic example of promissory estoppel, which is also known as detrimental reliance. You have reasonably relied on a promise, to your detriment and so you may be able to claim recovery under the equitable doctrine of promissory estoppel.