Follow-on is a rule in cricket matches having more than 2 innings. In international cricket its applicable to test cricket. Follow on is given to team playing in 2nd innings if it is short by a high margin(200 runs in test cricket) compared to runs made by team in 1st inning. This forces the team batting in 2nd inning to bat again in the 3rd inning as well.
Here is how the rules is goes on:
1) Team A bats in the first inning and makes huge score (say 550)
2) Team B bats in 2nd inning and scores 200 or more runs less than team A. (Say it makes 300 i.e 250 less than A)
3) Now, the captain of team A may ask for the team B captain to bat again.
4)If team B comes to bat in 3rd inning the following may happen,
i) It scores less than 250 runs (say 200). Then Team A wins by an inning and 50 runs.
ii) It score more than 250 runs (say 400). Then Team A must come to bat again. Its target now is 150 runs. If it gets it, Team A is winner otherwise Team B wins.
5) If team A decides to bat again in 3rd inning, the match continues as regular match.
Frequently asked questions:
1) When can a captain may or may not ask for Follow on:
Ans: As said earlier, if they lead by more than 200 runs they can ask for follow on. Still they may not if margin is small. As its difficult to bat in 4th inning, he may come to bat again and make the margin bigger and ask for other team to bat in 4th inning.
2) Is the rules for runs margin always 200?
Ans: In 5 day test cricket (which is official in International matches) 200 runs margin is the rule. But in domestic cricket where 4 day and 3 day matches takes place the rules for runs margin is smaller.