Application and Data Integration (ADI) is the use of software and architectural principles to bring together (integrate) a set of enterprise computer applications, with an emphasis on decoupling the data integration (application adaptors and message transformations) from the business processes that use the data. ADI uses middleware technologies such as an Enterprise Service Bus (ESB) as part of a service-oriented architecture as a means of integration.

Without integration, enterprise computing often takes the form of islands of automation, where the value of individual systems is not maximised because they are working in partial or full isolation. However if integration is carried out without following a structured ADI approach, many point-to-point connections grow up across an organisation. Dependencies are added on an ad-hoc basis, resulting in a tangled unmaintainable mess, commonly referred to as spaghetti, a comparison to the programming equivalent known as spaghetti code.