SNMP Version (v1 / v2c / v3)
If you are configuring SNMP for the first time, you might wonder which SNMP version to configure?
Out of the three versions, the SNMP version 3 is the most secure. It enables encryption and authentification of the SNMP messages but it's also more complex to configure on some devices. This is why a lot of people are using SNMP version 2c which only requires a password (named SNMP Community) and all the messages are not encrypted.
There are no reason to use version 1 except if it's the only version available on your device.
Here is a list of tutorials and manuals on how to configure SNMP on some devices. Note that only a read-only access is required (not read-write) and that SNMP Traps should not be configured to use the device monitoring feature.