In social-psychology, fundamental attribution error is the phenomenon where people judge other people and themselves in a different way. The person tends to judge other people's good behavior as them having a good personality and the person also judges other people's bad behavior as them having a bad personality. The error comes from the fact that the person judges themselves on the context or situation and not on personality. This can lead people to assume others are bad people instead of them making a mistake.
An example of this error would be if we had a person, who we will name Alice. Alice is a driver. Bob goes in front of her and Alice assumes he has bad personal qualities such as being selfish, being a bad driver, or being a jerk. However there are possible explanations that are related to context instead of personal qualities. Bob could have almost missed his flight, or his wife could be giving birth at the hospital. If she goes in front of someone else, she will likely make the opposite mistake and explain her behavior as situational instead of being a personal flaw. This is still the same error because it is an attribution (placement) that is wrong.