> For the complete documentation index, see [llms.txt](https://mudassirs46.gitbook.io/network-fundamentals/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mudassirs46.gitbook.io/network-fundamentals/tcp-transmission-control-protocol.md).

# TCP (Transmission Control Protocol)

TCP/IP [Transport Layer's](https://app.gitbook.com/@mudassirs46/s/network-fundamentals/transport-layer) TCP provides guarantee Delivery of Data.

* HTTP was built to get a  Web page from a Web Server for a Web Browser. If however the page is lost in between then the lower Layer's (Transport Layer's) TCP provides a Guarantee Delivery error recovery feature with the help of Re-Transmission & Acknowledgment.
* Each TCP Headers (encapsulated by Transport Layer) include Sequence Numbers & if a PC's Web Browser receives a response from a Web Server with Seq Numbers 1,3 & 4 it will automatically send a re-transmission request of a 2nd missing Segment thereby providing guaranteed delivery of Data. 

## Reference:

CCNA 200-301 OCG, Volume 1, Pg. 20-21 - Wendell Odom .