Internet

The internet is a global network of computers that works much like the postal system, only at sub-second speeds. Just as the postal service enables people to send one another envelopes containing messages, the internet enables computers to send one another small packets of digital data.

 For that to work, they use a common ’language’ called TCP/IP (Transmission Control Protocol/Internet Protocol).

How does it work?

First, you have to make a request. Let’s imagine you are visiting a web page with an image on it. How does the image get to your computer?

The image is hosted on a web server. Your computer sends a request to the web server for the image.

The request is sent in a ‘packet’. A packet is like a virtual parcel which has lots of important information attached to it. The two most important bits of information are the IP address of the web server that the image is stored on and the IP address of your computer.

Special computers called routers, and devices called switches, direct the packet from your computer to the web server. The web server might be close by or on the other side of the world. The packet can be sent across the world through fibre optic cables under the sea or even by satellite.

Now comes the receiving information part.  Now that the packet has arrived the web server opens it and reads your computer’s request, in this case, ‘please send me this image’.

Images are often quite large so they need to be split up into lots of packets, often hundreds or thousands of them. All of these packets include information about how they should be put back together as well as where they are going and where they came from. The web server sends these packets back to your computer and once again routers and switches direct them.

Now that all the packets have been received the information attached to them tells your computer how to put them back together and the image will display on your screen. This whole process of sending a request and receiving the packets usually takes less than a second!



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