A bond is an IOU (“I owe you”). The issuer — a government or a corporation — borrows your principal, pays a stated coupon at regular intervals, and returns the principal at the maturity date. Unlike a stockholder, a bondholder is a creditor, not an owner; the upside is capped at the contractual interest plus return of principal, and the downside in healthy bonds is correspondingly limited.
What that simple structure obscures is how many distinct instruments live under the “bond” label: Treasury notes, TIPS, I-bonds, EE bonds, municipal bonds (taxable and tax-exempt, AMT-free and otherwise), corporate bonds across the investment-grade and high-yield spectrum, zero-coupon bonds, callable bonds, sinking-fund bonds. Each has its own tax treatment, duration, credit risk profile, and place in a portfolio. The full treatment — pricing, yield calculations, ladder strategies, the role of bonds as portfolio ballast, the five fallacies the financial press repeatedly trips over — is in section “Bonds”. Tax-advantaged Treasury wrappers (I-bonds, EE bonds with their statutory step-up, TIPS) are covered in the same chapter.