A Simple Network Management Protocol (SNMP) Protocol Data Unit (PDU) is a block of data that is exchanged between SNMP managers and agents. It contains information regarding a certain aspect of the network, such as a device’s status, configuration, or performance. The PDU consists of a header and data fields, with the header containing information such as the message type and version, while the data field carries the actual data being transmitted. The PDU is the basic unit of data that is transmitted in the SNMP network management protocol.