Computer networking is the set of technologies that lets you surf the Internet
The Internet lets you surf the web, send an email, and talk to your grandmother on Skype or FaceTime. The Internet is a very large collection of computers and other connected devices all over the world.
In 1969, there were only four devices on the Internet (then called the ARPANET). Now there are more than three billion Internet users around the world.
Many of the devices on the Internet are computers - but not all. Gaming systems, smartphones, home security systems, home temperature systems, and even some cars can also be Internet-connected devices.
The Internet Backbone is a set of large networks that connect national and international networks together
The Internet is made up of separate large networks that are connected together. This collection of large national or international networks is called the Internet Backbone.
Each large network on the Backbone is operated independently. There are network standards that define how they connect to each other and share information. These defined standards allow them to connect and work together across the world!
When you send an email from the US across the world, say to Japan, how does it get there?
Internet Backbone networks are very high-speed networks
As the email travels around the globe, it crosses multiple networks on the Internet Backbone. These Backbone networks are very high-speed networks. In the US, companies such as AT&T, Level 3, or Sprint run these networks. Internationally, there are other providers for networks within the Backbone, like NTT in Japan, China Telecom in China, and more.
But your email doesn’t go right to the Internet Backbone and then to your friend in China. Your computer will be connected to the Internet Backbone through what is called an Internet Service Provider, or ISP. Although some ISPs also manage parts of the Backbone, not all do. There may be multiple steps between your computer and the Backbone. Each step in the journey is called a hop.
So your computer somewhere in the US will get to the Internet through an ISP. There may be multiple hops on the Backbone, and if you are sending your email to Japan, it will eventually cross over into NTT’s part of the Backbone. And then it will make its way to a local ISP, and finally to your friend.
WiFi is a standard to connect devices wirelessly
Before WiFi was in wide use, people used cables to connect their computers to their home routers, which were connected to their ISP. These days many devices are connected wirelessly to their home router. When you pick a WiFi network, you are picking a local wireless router that will allow you to connect and send and receive data wirelessly. WiFi is a network standard for connecting devices wirelessly to a local network. The standard defines how to connect, disconnect, and exchange data. Computers that network wirelessly have to follow the standard.
Many network standards define how different parts of the Internet work together
Many standards define how different parts of the Internet work together. The standards cover how to send and receive email messages, how to upload files, how to specify what a web page looks like, how to define a location on the Internet, and many more things. These shared standards are the reason that all these different devices and networks all over the world can work together.
Each hop on the network is connected through a device called a router
Each hop between you and your friend is connected through a device called a router. Routers can be small devices for local access to an ISP. They can also be complex devices for handling many, many transactions on the Internet Backbone – these are called Backbone Routers. For every type of network connection you can imagine, there is a router that implements that connection.
Routers figure out how to send information across the Internet from source to destination using addressing information from domain names (”foo.com”) or email address (”firstname.lastname@example.org”). These logical addresses map to physical destinations, just like your street address maps to your house!
The web is the part of the internet that web browsers can access