Embedded Event Manager (or EEM) is a tool that can be described as an action-reaction type utility. Thus whenever there is a certain trigger in Cisco IOS Logs a certain command or a group of commands can be configured to be automatically executed following a trigger.
There is a good description with examples on how to use EEM which also describes its basic functionality prepared by Ashish Shirkar (originally taken from https://supportforums.cisco.com/docs/DOC-27996) and saved in PDF format: File:EEM Basic Sample Configurations.pdf
By privilege15