Understanding TCP Segment Structure

TCP segments are the backbone of reliable internet communication but most people don't

understand their structure. Every time you load a webpage or stream a video,

TCP breaks your data into segments with a specific format. The header contains

critical fields like source and destination ports that identify applications, sequence numbers

that track data position, and acknowledgement numbers that confirm receipt.

Control flags like SYN, ACK, and FIN manage connection states during setup

and teardown. The window size field controls flow by telling senders how much data receivers

can handle. Checksums detect transmission errors while urgent pointers flag priority data.