Imagine you lend money to a friend—maybe for a car or a small business. You agree on the amount, when they’ll pay you back, and how much interest they’ll give you along the way. A bond works the same way, just on a much larger scale, with governments and companies as the borrowers. This chapter takes you inside the world of bonds: the contract details that define them, how to calculate what they’re really worth today, and how to think about the return you’ll earn.