In order to prove your case at trial, we must show that:

There was wrongdoing or someone was careless,
That the wrongdoing caused injury, and
That the injury is significant and/or permanent.

Causation is that vital link between the negligence and the injury that happened as a result of that wrongdoing.

As an example, a property owner was careless in not fixing a broken sidewalk. As a result, a woman fell and broke her hip.

“But for” the carelessness, this injury would not have happened.

Here’s the sequence:

Property owner owns sidewalk in front of his property.
Owner knew that over time, sidewalk cracked and because severely raised.
Owner received complaints from neighbors of dangerous condition.
Owner never fixed problem
Pedestrian walking her dog tripped over raised and broken sidewalk.
Had the sidewalk not been broken, she would not have tripped.
Had she not tripped, she would not have broken her hip.

The causation is the connection between the owner’s carelessness and her broken hip.