ELI5: Explain Like I'm 5

Assessor's parcel number

An assessor's parcel number (also known as an APN) is a number that is assigned to a piece of property by the government. People use APN numbers to identify which property they own or live in. The number is like a license plate for a car, but for real estate. Each piece of land or building has its own unique APN number that is used to make sure no one else gets confused about who owns what.