The linked article is an excellent primer around Ethernet in the modern era.
The only thing I could add on the basics side, is why Ethernet is actually a twisted pair of cables. The twist alleviates the possibility of EMI (electromagnetic interference) inference by ensuring there is no long, straight lengths of wire that would act as an antenna. Twisting the pairs causes the electromagnetic fields generated by each wire to partially cancel each other out, significantly reducing the overall interference picked up by the cable. This is known as common-mode rejection.
Twisting also helps eliminate crosstalk, which occurs when the signal from one wire leaks into another pair in the same cable. This can also corrupt the data signal and lead to errors. Twisting the pairs helps to keep the magnetic fields of each wire contained, reducing the amount of crosstalk between them.
See https://hackaday.com/2024/02/12/ethernet-for-hackers-the-very-basics/