What is aviation?
Aviation is the design, development, production, operation and use of required specifications for aircraft.
What is an aircraft?
A vehicle that can fly while taxiing, maintaining specific take-off weight, climbing, maintaining specific en route alt
itude, maintaining specific speed, descending, and landing safely.
Airplanes and helicopters are examples of aircrafts.
An aircraft counters the force of gravity by static lift or by dynamic lift of an airfoil or thrust from jet engines.
How many categories of aircraft are there at this point?
There are 10 categories of aircraft at this point.
Here are further guidelines.
https://qureshiuniversity.com/aviation.html