Steal bases

In most instances, the runner wont be able to complete an entire circuit of the bases on a single play, so he or she must stop at a base and wait for the next batter to step up to the plate. However, at any time, the runner may attempt to steal the next base by running to it before the pitcher realizes whats happening. Since the pitcher is usually the best thrower on the team, stealing a base is very dangerous the pitcher can turn and throw the ball to a baseman instead of the batter, allowing an easy tag out.
The basemen can also pass the ball to one another, trapping the runner between two bases until he or she makes a desperate (and usually futile) attempt to slide into one of them. Runners cant leave the line between the two bases, either theres no running off into the outfield and then circling back around, for example.
Runners are safe while on bases, but they arent required to stay on a base. Most runners prepare for a possible steal by scooting out a little ways from their current base, but not far enough that they cant scramble back to it if they have to.