Bond

A bond is an IOU you buy from a government or company: you lend them money, they pay you interest on a schedule, and they return your principal at the end. Boring and predictable — which is exactly the point. Bonds are the stabilizers of a portfolio, zigging when stocks zag.

Example: A $1,000 bond paying 4% sends you $40 a year, then hands back your $1,000 when it matures.