Final answer:
A small Unmanned Aircraft (UA) or drone in the US doesn't need to be registered if it weighs less than 0.55 pounds (250 grams) and is used solely for recreational purposes.
Step-by-step explanation:
In the United States, a small Unmanned Aircraft (UA), which is also commonly known as a drone, must be registered with the FAA before operation unless it weighs less than 0.55 pounds (250 grams) and is flown strictly for recreational purposes. The rule applies to drones that are used both for recreational and commercial purposes. However, if you're flying a drone that weighs under 0.55 pounds solely for recreation, you're not required to register it. That said, all drone pilots must adhere to the FAA's guidelines while operating their Unmanned Aircraft in the national airspace to ensure safety and compliance with regulations.