The double switch in baseball.

This explanation is explained assuming that the reader knows the rules of baseball already. If you don't know the rules I suggest you read Baseball Field Guide: An In-Depth Illustrated Guide to the Complete Rules of Baseball.

A double switch in baseball happens when the starting pitcher comes out of the game and the relief pitcher goes in.

So there are 2 teams playing right now, team 1 and team 2. It is the bottom of the 8th inning and Team 1 has two outs already. So this is team 2's batting order right now. Player H made the third out in the last inning.

1. Player A (second up)
2. Player B (third up)
3. Player C
4. Player D
5. Player E
6. Player F
7. Player G
8. Player H
9. Starting pitcher (first up to bat next inning)

So next time team 2 bats, the starting pitcher will bat first. So in the middle of the inning, the relief pitcher comes in the for the starting pitcher. So now it looks like this.

1. Player A (second up)
2. Player B (third up)
3. Player C
4. Player D
5. Player E
6. Player F
7. Player G
8. Player H
9. Relief pitcher (first up to bat next inning)

Most pitchers are very bad hitters and the relief pitcher is usually even worse. So when team 2 makes a pitching change, they want to make the double switch. Instead of the relief pitcher coming in for the starting pitcher, the relief pitcher will come in for another position. Let's say he comes in for Player H. At the same time, Player H's backup will come in for the starting pitcher. So now the relief pitcher and Player H's backup will switch position. So Player H's backup will be in Player H's spot and the relief pitcher will be in the pitcher spot. Now it looks like this:

1. Player A (second up)
2. Player B (third up)
3. Player C
4. Player D
5. Player E
6. Player F
7. Player G
8. Relief pitcher
9. Player H's backup (first up to bat next inning)

So now another player will start off hitting instead of the pitcher. Now the pitcher is the last to hit.