Stands for "Simple Network Management Protocol." SNMP is used for exchanging management information between network devices. For example, SNMP may be used to configure a router or simply check its status. There are four types of SNMP commands used to control and monitor managed devices: 1) read, 2) write, 3) trap, and 4) traversal operations.
The read command is used to monitor devices, while the write command is used to configure devices and change device settings. The trap command is used to "trap" events from the device and report them back to the monitoring system. Traversal operations are used to determine what variables a certain device supports.
SNMP has no authentication capabilities, which means it is not a very secure protocol. For this reason, SNMP is often used for monitoring networks rather than managing them. So, practically speaking, SNMP could be considered as a "Simple Network Monitoring Protocol" instead.