A flow is defined as a unidirectional sequence of packets with some common properties that pass through a network device. [...] for example, flow records includ

A flow is defined as a unidirectional sequence of packets with some common properties that pass through a network device. [...] for example, flow records include details such as IP addresses, packet and byte counts, timestamps, Type of Service (ToS), application ports, input and output interfaces, etc. From here: https://tools.ietf.org/html/rfc3954 https://tools.ietf.org/html/rfc3954