There are fundamentally two sources for our behavior; those influenced by external factors and those influenced by internal factors. Many factors play a role in how we allocate attributes to behaviors.  Obviously our view of the world, our previous experience with a particular person or situation, and our facts of the behavior play a significant role.  

Attribution theory is concerned with the ways in which people explain the behavior of others. It explores how individuals "attribute" causes to events and how this cognitive awareness affects their motivation. The attribution theory by Heider divides the behavior attributes into two parts.

• Internal attribution: When an internal attribution is made, the cause of the given behavior is within the person, i.e. the variables which make a person responsible like attitude, aptitude, nature and personality.
• External attribution: When an external attribution is made, the cause of the given behavior is assigned to the situation in which the behavior was seen. The person responsible for the behavior may assign the causality to the situation or weather.

In 1967, Kelley tried to explain the way people perceive internal and external attribution. He tried this, assume the principle of co-variation. This model was known as Co variation Model. The basic principle of the co variation model states that the effect is credited to one of the causes which co-vary over time. It also means that the behavior at various occasions varies. The co variation model considers three major types of information to make an attribution decision that are:

• Consensus information: This responds to the fact, how people with related stimulus behave in similar situations. If most people behave alike, i.e. their reactions are shared by many, the agreement is high. But, if no one or only a few people share the reactions, the consensus is low.
• Distinctiveness information: This is about, how a person responds to different situations. There exists a very low distinctiveness if the person reacts likewise in all or most of the situations. However, if a person reacts differently in different situations, it is said that the uniqueness is high.
• Consistency information: If the response of a person to different stimulus and in varied situations remains the same, then the consistency is high.

Usage and Applications of Attribution Theory of Social Psychology
The theory helps in Criminal Law, i.e. to understand the psychology of criminals. The usage of this theory here is of greatest importance. In today's times, with the increase in crime, particularly young crimes; understanding criminal psychology has become essential.
Attribution theory of social psychology is a solution to many problems the world is facing today. We can hope of a better world, with no crime, dishonesty and greed, only if the development in the theory is possible.