What is the difference between optimism and pessimism?

Julia, Optimism is a tendency to expect the best possible outcome. Optimists believe that the universe is always evolving toward good, that good triumphs over evil, and that people are inherently good. The traditional definition of an optimist is that you see the glass as half full instead of half empty. Pessimists see their role as diminished, insignificant, their lack of action shrinking the big picture to a pinhole. Optimists see the bigger picture and themselves as having a significant or meaningful role.