What are packets? (More Information)
A packet is a formatted block of information carried by a 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 a packet, the network can transmit longer messages more efficiently and reliably. A packet consists of three elements: the first element is a header, which marks the beginning of the packet; the second element is the payload, which contains the information to be carried in the packet; the third element is a trailer, which marks the end of the packet.
What is a packet sniffer? (More Information)
A packet sniffer (also known as a network analyzer or protocol analyzer) is computer software or computer hardware that can intercept and log traffic passing over a digital network or part of a network. As data streams travel back and forth over the network, the sniffer captures each packet and eventually decodes and analyzes its content according to the appropriate RFC or other specifications.