Development of information systems

An information system (IS) is a mechanism that helps people collect, store, organize, and use information. An information system includes a means of storing information, a set of procedures for handling information, and rules that govern the delivery of information to people in an organization. Traditionally, information systems were manual. One popular type of manual information system is the cardbased system, such as a card catalog in a library.
Because there are so many types of information and uses for it many kinds of information systems have been developed: office automation systems, transaction processing systems, management information systems, decision support systems, expert systems.
Office automation systems automate routine office tasks, such as word processing, accounting, document management or communications. Transaction processing systems not only track and store information about individual events but also provide information that is useful in running an organization, such as inventory status, billing, and so on. Management information systems produce reports for different types of managers. Decision support systems is a specialized application used to collect and report certain types of business data which can aid managers in the decision-making process. Expert systems include the knowledge of human experts in a particular area (such as medicine or technology) in a knowledge base. They analyze requests from users and assist the users in developing a course of action.
A well-structured IS department includes IS managers, computer scientists, systems analysts, programmers, database specialists, user assistance architects, technical writers, system or network managers, trainers, and hardware maintenance technicians. IS professionals support an organization's information, provide technical support for hardware and software and are involved in the design and implementation of an organization's entire information system.

Building Information Systems
The systems development life cycle (SDLC) is an organized method for building an information system. The SDLC includes five phases: needs analysis, systems design, development, implementation, and maintenance.
During the needs analysis phase, the development team focuses on completing three tasks: (1) defining the problem and whether to proceed, (2) analyzing the current system and developing possible solutions to the problem, and (3) selecting the best solution and defining its function.
During the systems design phase, the project team decides how the selected solution will work; each system activity is defined.
During the development phase, programmers play the key role: creating or customizing the software for the various parts of the system. There are two alternative paths through this phase: the acquisition path or the development path. The project team may decide to buy and then customize some components for an information system or develop the needed components themselves. Technical and user documentation is written during the development phase. Testing is also an integral
part of this phase.
In the implementation phase, the hardware and software are installed in the user environment. The process of moving from an old system to a new one is called conversion. The project team may follow four different conversion methods:
direct, parallel, phased, and pilot.
During the maintenance phase, IS professionals provide ongoing training and support to the system's users. Fixes or improvements are made regularly throughout the remaining life of the system.