"An IP address is a series of numbers that tells us where a particular device is on the Internet network, be it the google.com server or your computer. It's a bit like mom's phone number: just as the phone number tells an operator which house to route a call to so it reaches your mom, an IP address tells your computer which other device on the Internet to communicate with — to send data to and get data from."
The guidebook is actually a great example of an HTML5 web application that works offline and Google recommends to read it in "Chrome or any up-to-date, HTML5-compliant modern browser". Most of the examples from the book are about Google Chrome and that's what makes it look like a Chrome ad.
