An Anarchist FAQ is a great resource for most questions you might have about anarchism. A basic idea common to all forms of anarchism is that the absence of hierarchy would maximize individual liberty and social equality. The largest difference in anarchist schools of thought is between "individualist" and "social" anarchists, though their methods and ideas are not incompatible, and it is generally acknowledged that no theory is completely ideal for every time and place. As to the idea of a power vacuum, the process of an anarchist revolution is to dismantle the institutions that make it possible for an individual or organization to "swoop in and take" control. Also consider that anarchists do not disappear after a revolution: The widespread theory and practice that brought about massive change in society would necessarily stick around to maintain the new society. Anarchists who struggled through a revolution and their children who grew up in a culture of resistance would not submit to a new ruler.