Why have we created a world where our word is no longer our bond? Why is practically everything we do governed by contracts? Footballers and film stars crave them and insist on their personal clauses; lawyers pore over their fine print to protect their clients; and lovers stipulate just how they expect their partners to behave.
We use contracts if we want to buy a house.
We use them to make sure we're not exploited at work and we all enter into them unwittingly even when we're just popping down to the supermarket for some groceries.
The BBC's Economics Editor, Evan Davis, investigates what contracts are, why they succeed or fail, and why we have become so obsessed by signing on the dotted line.