The order of innings in a match where the follow-on is enforced is as follows:
This contrasts with the conventional order of innings (when the follow-on is not available or not enforced):
The decision to enforce the follow-on is made by the captain of the team that batted first, who are in an advantageous position. Enforcing is intended to reduce the chance of the match being drawn, as the follow-on means that both of the trailing team's innings will be completed sooner. This decision to enforce or decline the follow-on is made after considering the state of the game, the conditions of weather and pitch, the apparent strength of the two sides, and the time remaining.
The follow-on only occurs in forms of cricket where both teams bat twice (for example domestic first class cricket or international Test cricket). The rules governing the circumstances in which the follow-on may be enforced are found in Law 14 of the Laws of Cricket.
An example can be seen in the Second Test of the India national cricket team's tour of Sri Lanka in 2017. In this Test, India won the toss and chose to bat first. Sri Lanka batted second, and were then forced to follow-on, after failing to reach within 200 runs of India's first inning score. Therefore, the order of innings in this Test (which India won by an innings and 53 runs) was: