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Your Device
Application Layer
Transport Layer
Internet Layer
Link Layer
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Internet
Web Server
Application Layer
Transport Layer
Internet Layer
Link Layer
You want to load a website
You type 'www.bbc.co.uk' into your browser and press Enter. Your computer needs to send a request to the BBC's web server somewhere on the internet. The request will travel down through all four layers before leaving your device.
What each layer does
ApplicationCreates the data and decides what format to use (HTTP, SMTP, FTP...)
Transport (TCP)Splits data into numbered packets, reassembles them, checks for errors
Internet (IP)Adds IP addresses and routes packets across the internet via routers
LinkConverts packets to signals and sends them over a cable or Wi-Fi