What is stall of an aircraft?

Answer 1As an airplane's wing moves through the air, the faster moving air on the top of the wing creates a low pressure zone or "lift" which keeps the airplane up and flying.

If anything happens to deflect or destroy that proper airflow (smooth flow of air around the wing) the wing loses lift, and is said to stall.

This could be from loss of speed or too much angle of attack (pulling back to hard)

In many cases the actual stall is preceded by a buffet (shaking) In Many cases you can avoid the stall by lowering the nose of the aircraft.

A spin is an aggravated stall

Yes that is true but another reason an aircraft could stall is because the service celing of the aircraft has been reached the aircraft can no longer produce enough thrust to keep it in the air because the air is too thin or the engines aren't strong enough