The airspeed indicator or airspeed gauge is an instrument used in an aircraft to display the airspeed in knots

An airspeed indicator is an aviation instrument which displays an aircraft's current airspeed.

Equivalent airspeed is speed at sea level in which the incompressible dynamic pressure can be produces as if it were at true airspeed. Equivalent airspeed is used to predict aircraft handling.

That one can be tricky.

Airspeed is speed WRT the air, but air can be moving. If it is, you have to compensate for the movement of the air to get an accurate conversion between airspeed and speed over ground.

If you assume the air to be stationary, it's easy. One nautical mile is about 15% more than a mile.

So 1 knot = 1.15 mph

1 mph = 0.85 knot.

Airspeed Aviation was created in 1986.