There are entire series of books dedicated to how networks communicate; this chapter will begin with some very basic information. If you have already understood this data, I encourage you to read through it as a refresher, just in case some new or different details are covered. Additionally, there are some references to the sizes of header components and payloads. These are specifics on how the network protocols are referenced, and how the protocols could be different depending on what data is being transmitted and/or the differences in specialty networks.
As a system generates data, it is sent down through the system's Transmission Control Protocol (TCP) / Internet Protocol (IP) stack. This packages the data into something that can be transmitted over the wire. If you have heard of the Open Systems Interconnect (OSI) model, then you know that this is how people discuss how systems process data, whereas the TCP/IP Model is the way systems actually operate...