What is Delta V (Dv)

What is Delta V (DV)?

  Delta v (Dv) or (ΔV)  Delta V is the ability to change your situation in space.  Delta V is actually  Δ Velocity  or change in velocity.    

Simplest Situation in explanation You are trying to match orbits with another craft you are traveling at 2600m/s and the other craft is traveling at 2500 m/s  you want to be traveling at the same speed.

 It is going to cost you 100 m/s Delta V to achieve a matched velocity.

Another Simple use of Delta V.  You are orbiting Kerbin at 80,000 meters (circular) and you want to go to the mun.  When the mun is rising you use 860 m/s Delta V burning prograde to get an apoapse close to the Mun's orbit.