> For the complete documentation index, see [llms.txt](https://til.notdu.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://til.notdu.com/back-end/network/the-internet/protocol-stacks-and-packets.md).

# Protocol Stacks and Packets

Your IP address is 1.2.3.4 and you want to send a message to the computer 5.6.7.8

The message must be translated from alphabetic text into electronic signals, transmitted over the Internet, then translated back into alphabetic text through the use of a **protocol stack.**

![](https://2548495579-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTsnKOX7xLvOtvOXY9MlI%2Fuploads%2F2EUWCk8fV6Zvy3f8Wctc%2Fimage.png?alt=media\&token=d3de3370-5926-4b84-9efa-e33e7c5f5985)

* The message maybe break up into smaller chunks of data, which called packets
* Each packet is assigned a **port number** in the TCP layer