United States — FAA
Federal Aviation Administration
In the US, the FAA issues pilot certificates under 14 CFR Part 61 (or an approved Part 141 school curriculum). Pilots generally progress from Private to Commercial, add an Instrument Rating, and finish at the Airline Transport Pilot certificate needed for airline operations.
Europe — EASA
European Union Aviation Safety Agency
EASA licensing (Part-FCL) applies across EU member states, with each national authority issuing the licence to a common standard. The usual route is PPL, then CPL, with an Instrument Rating, leading to the ATPL — the licence airline captains hold once experience requirements are met.