The term configuration item or CI refers to the fundamental structural unit of a configuration management system. Examples of CIs include individual requirements documents, software, models, and plans. The Configuration management system oversees the life of the CIs through a combination of process and tools by implementing and enabling the fundamental elements of identification, change management, status accounting, and audits. The objective of this system is to avoid the introduction of errors related to lack of testing as well as incompatibilities with other CIs.
Role in configuration management 
The term configuration item can be applied to anything designated for the application of the elements of configuration management and treated as a single entity in the configuration management system.
- The entity must be uniquely identified so that it can be distinguished from all other configuration items.
- From the perspective of the implementer of a change, the CI is the "what" of the change. Altering a specific baseline version of a configuration item creates a new version of the same configuration item, itself a baseline. In examining the effect of a change, two of the questions that must be asked are:
- What configuration items are affected?
- How have the configuration items been affected?
- Its use within a product can be traced in a robust status accounting system.
- It is subject to acceptance verification based on established criteria.
A release (itself a versioned entity) may consist of several configuration items. The set of changes to each configuration item will appear in the release notes, and the notes may contain specific headings for each configuration item. A complex hardware configuration item may have many levels of configuration items beneath its top level; each configuration item level must meet the same fundamental elements of the configuration management system.
In addition to its purpose in the implementation and management of a change, each configuration item's listing and definition should act as a common vocabulary across all groups connected to the product. It should be defined at a level such that an individual involved with product marketing and an individual at the coalface of implementation can agree to a common definition when they use the name of the lection and identification of configuration items for a particular project can be seen as the first step in developing an overall architecture of the product from the top down.
Configuration items, their versions, and their changes form the basis of any configuration audit.