VSpeed

V-speeds are standard terms used to define airspeeds important or useful to the operation of all aircraft (including fixed-wing aircraft, gliders, autogiros, helicopters, and dirigibles)
These speeds are derived from data obtained by aircraft designers and manufacturers during flight testing and verified in most countries by government flight inspectors during aircraft type-certification testing.
Using them is considered a best practice to maximize aviation safety and aircraft performance.
The speeds are specific to a particular model of aircraft, and are expressed in terms of the aircraft's indicated airspeed, so that pilots may use them directly, without having to apply correction factors.
Proper display of V speeds is an airworthiness requirement for type-certificated aircraft in most countries.