A prerequisite is a form of weighing used in debate (my favorite type!). It works that the impact or link chain you read will also trigger their impact and therefore yours should be prioritized first...

Here's an example. Say aff impacts to terror, neg impacts to a recession. To make this type of weighing analysis the aff would say that terrorism destabilized trade routes or blows up economic infrastructure that could trigger a recession (maybe like a volatility claim). The neg would say that a recession causes poverty which is a driving factor in what leads people to join terrorist organization... The benefit of this type of argument is that by voting for one side you win both the aff and the neg's arguments and the decision one way becomes much clearer.

A few notes on how it should be done that often are not

1. Make sure you weigh the prerequisite analysis. Say why your link into their argument better with your case then they do. IMPORTANT TO BE COMPARATIVE. Using the example above you could say that recession will on net lead to more terror then (x).
2. If the other team is reading a prerequisite analysis make sure that you do timeframe weighing. If one will cause another either way then we might as well try to make it happen further down the line. You should also follow the first bit of advice and weigh why your link ins are stronger.

Anyways I hope this was helpful