A few links we point people to. If you're curious about flying drones for work, start here.
If you fly a drone for work, even to shoot a roof for a customer, the FAA requires a Remote Pilot Certificate. People call it a Part 107 license. Flying only for fun is different, and the next section covers that.
Rules and links change. The FAA pages on the right are the official source, so go by those.
If you only fly for recreation, you don't need a Part 107 license, but you do need to pass a short free safety test called TRUST. The FAA has the details.