...are a necessary evil in roleplaying. On one hand they are needed to move the action along in a manageable fashion, and on the other they can very easily become too cumbersome and destroy the action altogether.
Take a moment to think about the rules in a roleplaying game. What purpose do they serve? In most systems, they first provide "balance," ensuring that the characters are not too powerful in relation to the world or to one another. Second, they provide flavor. The way in which the system describes characters naturally affects how you perceive those characters.
But both of these are somewhat secondary to the core purpose of the system: to decide which way the story will go at certain critical points. Will the troupe successfully find the secret door, or will they be trapped? Will they be able to pick the lock? Leap to the next train car? Defeat the enemy in battle? These are the times when the actors are no longer directly in control of things, and the characters choose their own fate by their abilities, luck, and instincts.
The Window provides the means of making these random plotting decisions through simple, quick, and easy to remember mechanics. The core rules can be learned in about five minutes and can be adapted to any genre you like in about ten. After reading the three precepts and the quick start page, you will be more or less ready to start playing. The majority of the sections afterward are concerned with presenting examples and discussing all the finer details.
There are a few terms used in the Window which need to be clarified. The Storyteller is what other systems call the Gamemaster or Referee, based on the idea that the story is more important than any game or sport. The players are called actors, since that is what they truly are. We refer to the party of characters as the cast or the troupe.
In fact, theatrical and literary terms are used at all levels of the story, from a scene, to an act or chapter (one "adventure"), to a book (a "campaign," like a self contained series of acts), to the anthology or setting (all the books and characters which constitute a single world.)