Packets

Packet - A unit of data sent on a packet switching network.

Header - Part of the packet that store destination address, source address and packet number

Payload - The part of the packet with the actual data. Can be also known as the body

Footer - Part of the packet that contains a checksum. 

Check sum - A form of validation used to check that the payload data hasn’t been corrupted during transit. 

Packet-Switching - The process of directing data  packets on a network using routers and the IP protocol