How can Aircraft fly in the air?

1.How does an aircraft stay up in the air?

In general, the wing’s upper surface is curved so that the air rushing over the top of the wing speeds up and stretches out, which decreases the air pressure above the wing. In contrast, the air flowing below the wing moves in a straighter line, thus its speed and pressure remain about the same. Since high pressure always moves toward low pressure, the air below the wing pushes upward toward the air above the wing.

2.What is the Bernoulli Principle?

Air, like water, is a fluid; however, unlike water, which is a liquid, air is a gaseous substance. Air is considered a fluid because it flows and can take on different shapes. Bernoulli asserted in “Hydrodynamic” that as a fluid moves faster, it produces less pressure, and conversely, slower moving fluids produce greater pressure.

from:https://www.nasa.gov/sites/default/files/atoms/files/bernoulli_principle_k-4.pdf