What is cognitive dissonance? List one example of this state of psychological te

In psychology, cognitive dissonance is the excessive mental stress and discomfort experienced by an individual who holds two or more contradictory beliefs, ideas, or values at the same time or is confronted by new information that conflicts with existing beliefs, ideas, or values. This stress and discomfort may also arise within an individual who holds a belief and performs a contradictory action or reaction.
Here are some examples of the Cognitive dissonance theory:

Example 1: Knowing that smoking is harmful (First cognition) while liking to smoke (second cognition). The Cognitive dissonance theory's conditions were met because those cognitions are dissonant
Example 2: Believing that lying is bad (First cognition) and being forced to lie (second cognition)
Example 3: Liking a friend (first cognition) while knowing that he hates your brother (second cognition)