Overview of Requirements Engineering

Software requirements engineering is the process of determining what is to be produced in a software system. In developing a complex software system, the requirements engineering process has the widely recognized goal of determining the needs for, and the intended external behavior, of a system design. This process is regarded as one of the most important parts of building a software system.
Requirements engineering is an important aspect of any software project, and is a general term used to encompass all the activities related to requirements. The five specific steps in software requirements engineering are:

* Requirements inception
* Requirements elicitation
* Requirements analysis
* Requirements specification
* Requirements validation

Although they seem to be separate tasks, these four processes cannot be strictly separated and performed sequentially. All four are performed repeatedly because the needs are often impossible to realize until after a system is built. Even when requirements are stated initially, it is likely they will change at least once during development, and it is very likely they will change immediately after development.