(Enterprise Application Integration) The various techniques used to make information systems work together in the large enterprise. For example, when companies acquire other companies, disparate systems have to be integrated. Within a company, newly developed systems must work with legacy systems, and separate systems developed independently in the past must often be tied together to provide required information and services. When information systems are integrated, business intelligence can be gleaned across the entire enterprise.EAI software may function as a central distribution hub, providing data and command conversions where necessary between applications. It is also a major component of a business process management suite (see BPM). See middleware and application integration.EAI, EII and ETLEAI often entails conversion from one format to another and differs from EII (enterprise information integration), which aggregates current information from disparate sources. EAI also differs from ETL (extract, transform, load), which migrates data from one database into another. See EII and ETL.