SNMP stands for Simple Network Management Protocol, and is a way to directly address not just individual hardware elements, but to access specific functions or methods within that device via a "simple" addressing scheme. A MIB file describes the various endpoints available on a device, much like a wsdl file would describe a SOAP endpoint.
So you might have an SNMP address like 2.1.4.3.0.1* which the MIB file would translate to "the current temp for CPU1"
So you might have an SNMP address like 2.1.4.3.0.1* which the MIB file would translate to "the current temp for CPU1"