Microeconomics -Efficient or not?

Market efficiencies and inefficiencies happen all around us. Consider the definition of perfect competition and give an example from your personal life.

Now, consider the four sources of market failure and examine how each led to an inefficient allocation of resources. Take a moment to look around you and give an example for each of the four sources of market failure. Why do you feel these are good examples?

Discussion post.  Just a few sentences for each question.