Wireless Routers, Peeling Lips What Is The Difference Between Wireless "G" And Wireless "N" Routers?

What is the difference between wireless "G" and wireless "N" routers? - wireless routers, peeling lips

Facing a first laptop (buy) and purchase intention, of course, a wireless router as well as on. I noticed that some Wireless-G and Wireless-N, and so on. Is there a difference? Some laptops come only with certain wireless router? How do I know?