Information system (IS)	A kind of system that produces outputs we humans can process. A data processing system. Can be a paper-based, mechanical or electronic system. Usually a computer application that processes data for use by people in a business system.
User	An actor outside the boundary of the system being used. Usually a human being. A role or individual who uses an application. “Person that daily uses IT services.” ITIL
Application	A system of software components that supports business functions and services; for example, benefit payments. Applications usually depend on one or more data stores, and are supported by application platform technologies. May take the role of a client or server. Should be discrete and deployable. Important characteristics include size, owner, cost, value. May be divided into business, infrastructure and platform applications.
Business application	An application that helps its users to perform business-specific tasks. E.g. order entry system, management information system. Business applications may be divided into front-office or Business Support Systems (BSS) and back office or Operational Support Systems (OSS).
Infrastructure application	An application that helps its users to perform generic office and administrative tasks. E.g. a browser, word processor, spreadsheet.
Platform application	An application that supports business applications – a component of the application platform. E.g. a message broker, DBMS or operating system.
Enterprise Resource Planning (ERP)	ERP is the planning of how enterprise resources (materials, employees, customers, etc.) are acquired, moved from one state to another. An ERP system is a operational and business support system that maintains (ideally in a single database) the data needed for some or all of Manufacturing, Supply Chain Management, Financials, Projects, Human Resources, Customer Relationship Management, Data Warehouse and Management Information.
Customer relationship management (CRM)	CRM is the development and maintenance of mutually beneficial long-term relationships with customers. It helps with some or all of the following: attracting customers, transacting business with customers, servicing and supporting customer, enhancing customer relationships. A CRM system is a business support system that helps this relationship management.