What is a 'base runner' in baseball?

What is a 'base runner' in baseball?

Alan Jaeger (Pitching Coach / Founder) gives expert video advice on: What is a 'base runner' in baseball?; What do I do after I hit a fair ball?; After I hit a fair ball how should I judge how many bases I can take? and more...

A base runner is really the hitter once he puts the ball in the play. Once the ball is in the fair territory, he becomes the base runner. Once you leave home play, and leave the batter's box you are officially the base runner.