The following explanation and examples are intended to teach how to apply Minute of Angle (MOA) terminology to shooting, not how to do the Trigonometry involved in calculating Minute of Angle (MOA).
If you would like to learn how Minute of Angle (MOA) is calculated and where the term comes from please visit this Wikipedia link.

If you are already a Minute of Angle Expert, take our Minute of Angle Quiz

You should understand that an English inch and a Minute of Angle (MOA) is not the same thing. They are units of measurement that happen to be extremely close in value. However, they are close enough together that for the rest of this explanation please simply round down to an inch.

In speaking with both experienced and inexperienced shooters I have come to the conclusion that the majority of shooters have no idea what their bullet does after it leaves their gun. It is essential in good shooting and sportsmanlike hunting to understand your bullets trajectory. To really get first-rate information it’s important to use an accurate ballistics calculator. There is no good excuse for not knowing what your bullet does as there are many free exterior ballistic calculators and websites available that can give you very accurate information. If you are going to shoot at game it is also important to verify the information out to at least the range you would shoot at game. By verify I mean take your gun and the loads you will be hunting with and shoot them at the ranges you will be hunting at to make sure the ballistic calculator matches what your bullet does in the real world.