# Hierarchical Indexing

This chapter explains the hierarchical structure of HEALPix.

## Hierarchical Navigation

Each cell has:

- 1 parent at the top level
- 4 children at the bottom level
- Neighbors at the same level

For more details, see:

- {doc}`../tutorials/quickstart` - Section on Hierarchy
- {doc}`../healpix/index` - HEALPix Structure
- {doc}`../api` - Navigation Functions