ELI5: Explain Like I'm 5

Apple partition map

An Apple Partition Map is like a map that tells your computer where files and programs are stored. Each part of the map is like a little spot on the map that is numbered. On an Apple computer, the hard drive is divided into different parts, like states or countries on a map, and each part is labeled with a number. The Partition Map makes it easy to find the information stored on the computer. Every time you open a file or use a program on your computer, the Partition Map helps your computer find it.