The Operations Working Group internally classifies services it runs as primary, secondary, and tertiary. This allows us to prioritise when budgeting and planning systems.This policy sets out grounds for classification and a current list of each service.
Our primary services are the editing API and raw OSM data downloads. Any internal services required to enable these are therefore also considered primary services.
Secondary services are services which are used for editing but not a requirement, and only the OSMF could run them; or essential to the experience on osm.org, but others could run them.