We've already learned about the base runner and how they are trying to become safe on-base. In order to be called safe by an umpire, the base runner needs to touch the bag with a part of his body. Sometimes, running towards a base just won't cut it.
Sliding is a technique that base runners use in order to avoid being tagged out with the baseball. When a base runner approaches a base, and a fielder near him has the baseball, the runner will drop to the ground and -- using his momentum from running -- slide feet-first into the base. Although sliding seems counterintuitive since it actually is slower than running, it is harder for fielders to tag a runner who is sliding. Base coaches are allowed to leave the coaches' box when directing a player to slide.
Yes, sliding is allowed on first base, but it is not recommended since a batter-runner can overrun the base which is faster. When sliding to first base, the runner is allowed to leave the running lane within a reasonable distance for the purpose of getting on base.
Diving is a form of sliding, except runners drop on their stomachs and go toward the base head/hands-off rather than feet-first. For players, diving often hurts more than sliding.
Runners are allowed to slide into other bases besides first base, but will be called for interference if they slide just to break up a double play. Fielders are not allowed to block the base paths. In this case, the fielder will be called for interference. Runners can use their hand or foot to touch the base and be safe.
Sometimes, a player will have too much momentum or begin his slide too late, therefore sliding too far or too fast past the base and not making contact with it. In this situation, it is more likely that the fielders will be able to tag him out. A batter-runner cannot be tagged out if he overruns or overslides on first base as long as he immediately returns to the base after the slide. However, this is not the case if the player is a base runner. If the batter-runner chooses to run towards second base, he can be tagged out. Runners can get out from oversliding or overrunning at other bases from a force out or a tag out based on if there was force on the play.
What happens if a base runner makes contact with the catcher when sliding into home plate? If the runner has his body on the ground prior to making contact with the catcher, it is a legal slide. On a slide, his legs and butt must be on the ground. For a dive, his body must make contact with the ground. It is not the runners fault, if the catcher chooses to block the path to home plate. Catchers are only allowed to block the running path if they have the ball.
When a player chooses to slide, oversliding and is tagged out before returning to base, the official scorer will record a base-hit or hit based on the number of bases he reached safely. The official scorer will record a caught stealing stat when a player overslides on a steal.