What is the best definition of a Configuration Item (CI)?

Configuration item (CI) is an asset, service component or item that is, or will be under the control of Configuration Management. CI may be a single module such as a monitor or a tape drive, or a more complex item, such as a complete system. It needs to be managed in order to deliver IT service.

Information on each configuration item is recorded within configuration management system and this is maintained throughout its life cycle.

Structure and attributes of a contribution item are organizational specific depending on maturity and how they manage the assets.