A reversal is when things go from bad to good or good to bad for the protagonist. An example would be your main character winning the lottery and then, in the midst of the excitement, he loses the winning ticket. The mood would go from happy excitement to depression and anger.
A discovery is when the protagonist finds something that will help her unravel a mystery or solve a problem. A perfect example of a discovery is when a detective uncovers a vital clue.
When reading a good book, there will always be a scene where you wonder just how the main character is going to get out of or fix the situation. A complication is when something arises that seems to screw everything up. The main character is caught in a muddle. An example of a complication would be when a CSI thinks she has identified the murderer and discovers that she is wrong. All her discoveries have led up to this moment and now she is caught up in a complication.
A catastrophe is when the worst happens. It is the lowest point in the story. An example of a catastrophe would be when a detective's partner is killed by the bad guy.
The recognition in a story happens when the main character comes to a deeper understanding of himself, his situation, or another character. It is the aha moment of the story. Now it all makes sense.
The resolution is when the goal is met or the problem is solved in the story.