Optimists are a dying breed in this day and age. To the optimists, the world is a positive place. Everything is inherently good, and all things will work out in the end. They believe violence will one day be replaced with logic and reason, and that all religions can coexisist peacefully. These are the people who always see the glass half full, and believe that we live in the best possible world.
Famous optimists include: Gottfried Leibniz, William Godwin.
The opposite of Optimism is Skepticism.