Placekey is a system for encoding points of interest (POIs), and incorporates H3 in its POI identifier.
For example, the Placekey for the Ferry Building in San Francisco,
zzw-22y@5vg-7gt-qzz, contains a What Part (
zzw-22y) encoding a specific POI, and a Where Part (
5vg-7gt-qzz) encoding where that POI is. The Where Part is an H3 cell index at resolution 10, using an alternate string encoding. The example Where Part represents the H3 index
8a283082a677fff. Placekey Where Parts can be losslessly converted to and from their equivalent H3 indexes.