The study of attribution goes back to 1958 with Heider's proposal that all individuals have a social tendency to explain events based on what they perceive. While this sounds obvious, the actual process of understanding how the human mind discerns, makes conclusions, and attributes traits is, in itself, a systematic chain of events that is worthy of in-depth study.
This being said, attribution theory aims to explain the ways in which humans give meaning to the behaviors that they witness. It is mainly a theory of perception. The study entails that people have a natural tendency to find a cause, or a rationale, that helps to explain everything. It is also part of our brain activity; the human brain tends to think in a cyclical way, always wanting to find closure for every situation it experiences.
Fiske and Taylor (1991) brought up the actual definition of "an" attribution theory in a way that had not been done previously. In their own words, this theory
...examines what information is gathered and how it is combined to form a causal judgment
The most important thing to consider is the premise of A.T: It says that we, as individuals, always give meaning to behaviors, even automatically. When we apply emotion, personal experiences, traumas, and ready-made connections to our thinking processes, the affect may interfere with the proper judgement of what a behavior really means. This is one of the primary causes of discord and miscommunication in nearly every relationship.
For example: If you have always had bad dates in your adult life, you may have already made assumptions as to what the person dating you is feeling based on specific facial expressions. This is when the question "What is that supposed to mean?" causes so many fights.
Similarly, if you are traumatized by a childhood event, you may transfer what you saw as a child to what you see in others as an adult. This is when people get pet peeves about the way someone looks at them or sounds to them. It is entirely a subjective process, and this is why it is worth studying.