Networks addressing and protocol
Packets
In computer networking, a packet is a formatted unit of data carried by a packet mode computer network. Computer communications links that do not support packets, such as traditional point to point telecommunications links, simply transmit data as a series of bytes, characters, or bits alone. When data is formatted into packets, the bitrate of the communication medium can be better shared among users than if the network were circuit switches.
protocols
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications. A protocol may have a formal description. Protocols may include signaling , authentication and error detection and correction capabilities.
"protocol is a set of of rules that define how computers and devices communicate"
Mac address
an individual code that no other computer can have