As with TCP and UDP, the IP protocol also has a header:
I've very rarely looked at headers of either TCP, UDP, or IP in my career. It's just not required at the public Cloud level. Still the only headers of note here are the: source and destination address, TTL and protocol.
The source and destination headers contain the address of where the packet is coming from and where it's destined to arrive at.
The TTL, or Time To Live, is how many routers (called "hops") the IP packet can try to traverse through before all routing efforts are stopped (this is how ICMP/ping works, which we cover next.)
And the protocol field is used to contain the protocol - like TCP or UDP - that the IP packet encapsulates.