The ABC model in CBT helps you react to negative situations in a better way.

A - Activating Event/Trigger

The stimuli/external event(generally negative) that triggers you.

Eg. You saw a friend on the street - but he did not smile at you.

B - Belief(Assigned Meaning)

The automatic thoughts that assigns a meaning to the event. People don't know the existence of this layer. They think of their automatic thoughts as the truth - rather than just a belief.

You can change this to change the final response.

Eg. You think that the friend is ignoring you.

C - Consequence(Response)

The result of the event and the belief. It can be an emotional response or a behavior/action that you do.

Eg. You are angry at your friend because they ignored you. If you can change the belief to "the friend did not see you", the consequence will not be anger.