In micro, macro, and international trade courses, the concept of a perfectly competitive market is used as a benchmark. With externalities, we use the competitive market outcome to determine deadweight loss and socially optimal outcomes. As you'll see going forward, we do the same comparison against monopolies, oligopolies, and monopolistically competitive markets. In the real world, we often talk about "competitive markets", which isn't really the same thing. Questions to Answer In This Deep Dive Are there any real-world examples of perfectly competitive markets? Are "highly competitive" markets a good enough proxy? Is there an example you'd use