In System Center Essentials 2010, a Management Pack begins monitoring as soon as it is imported into a managed network environment. To accomplish this, a Management Pack contains default settings and thresholds that are set by the vendor of the Management Pack. These settings represent the vendor's definition of a healthy state for its product. You can use overrides to adjust these default settings and customize them for your network.
Imported Management Packs have monitors, attributes, object discoveries, and rules that are targeted at types of objects, also known as classes, on your network. Often these object types are broad in scope. Because overrides can apply to a group of managed objects, you can use overrides and groups to hone the data collection of these monitors, attributes, object discoveries, and rules to collect only the information that you need. For more information about this, see Targeting.
You can view which overrides affect a managed object by viewing the override summary of the object. You must have at least Advanced Operator user rights to create and edit overrides.