A MIB file is a text file that defines all the OID’s available in that file.
If you look at this file it will be hard to understand, which is fine.
That is why MIB browsers where made.
MIB browsers where made to interpreted MIB files and make it easier to understand each OID.
Each OID will have a name, a description as well as if SNMP Get’s or Set’s are accepted.
Most MIB browsers also have a built in feature to send SNMP Get's and Set's.
This is great when looking for the right OID.
Using the find feature "Ctrl+F" is very helpful in finding the correct OID you need.
Download any third party MIB browser. iReasoning
is free for non commercial use. iReasoning MIB browser and Extreme Management MIB Tools will have most of the RFC standard MIB files included.