How Does the Internet Work?

Guest Post by Jason M. Rubin from the Ask an Engineer series, published by MIT’s School of Engineering

Some people talk about cloud computing all the time, but they have their heads in the clouds if they think online information—web pages, music files, videos, and the vast seas of images and data—floats about magically in the ether, miraculously channeled through our laptops and smart phones. The Internet is not a magical cloud, explains Devavrat Shah, Jamieson Associate Professor in MIT’s Electrical Engineering and Computer Science department. It is a decidedly real collection of wires, optical fibres, electromagnetic waves, computers, and datacenters.

Understanding email is a good first step, Shah says. “A suitable analogy is the postal service. It uses an addressing system that enables a letter to be delivered to a specific place. The Internet does the same thing with emails. An email account is a specific unduplicated address.” There is, for example, only one askanengineer@mit.edu email address on the whole Internet.

When it comes to Facebook, Google, Netflix, or any other web destination, the situation is not so different. Facebook, for example, is a “virtual place,” Shah says, and its address is expressed as a URL, or a uniform (or universal) resource locator. When you type the URL of someone’s FB fan page, or your own page, into your web browser, the Internet takes you to that exact location – or, more accurately, it delivers that Facebook location to you by using a network directory service called the Domain Name System (DNS). Hosting more than a billion users, the Facebook you see on your computer actually lives on many servers in many different datacenters. Read more.

Visit the MIT School of Engineering’s Ask an Engineer site for answers to more of your questions.