Integration (from the Latin integer, meaning whole or entire) generally means combining parts so that they work together or form a whole. In information technology, there are several common usages:
1) Integration during product development is a process in which separately produced components or subsystems are combined and problems in their interactions are addressed.
2) Integration is an activity by companies that specialize in bringing different manufacturers' products together into a smoothly working system.
3) In marketing usage, products or components said to be integrated appear to meet one or more of the following conditions:
A) They share a common purpose or set of objectives. (This is the loosest form of integration.)
C) They were all designed together at the same time with a unifying purpose and/or architecture. (They may be sold as piece-parts but they were designed with the same larger objectives and/or architecture.)
D) They share some of the same programming code.
E) They share some special knowledge of code (such as a lower-level program interface) that may or may not be publicly available. (If not publicly available, companies have been known to sue to make it available in order to make competition fair.)