ILM – Information Lifecycle Management. This is the concept of data (information) having a lifecycle from its birth to its death or near death as the rate of access to apiece of information slows over time. Imagine an online order being made. The transaction data is used a lot when the transaction is first made, when it is primary data. It is referenced by a payment subsystem and also by a delivery subsystem. A product system might use it. Then the information becomes secondary and is used for reference in, for example, weekly sales analyses and then, monthly and, eventually, yearly, at which point it is nn a tertiary phase. After that it may be archived for use at longer intervals, or even deleted. That is its lifecycle from creation (birth) to deletion (death). A corresponding idea is that it should be stored on different storage media at the different periods in its life, to reflect the need for less urgent access, and his less expensive storage, as it ages. See the HSM (Hierarchical Storage Management) entry.