“Negligence” is a legal word that refers to the failure to use the care a normal person would use. A person or business who is negligent either: (1) does something a reasonable safe person wouldn’t do (like failing to stop for a red light); or (2) fails to do something a reasonable business would do (like failing to regularly check the tires and brakes on its trucks).
Negligence is the legal standard for determining responsibility. If someone is harmed because someone else was negligent, the injured party has the legal right to be compensated for the damage done to them. It’s up to people to be careful and prevent accidents they could avoid. If they don’t use care, they are responsible to make it right.