The V-model is a process model in software development, where the software development process is organized in phases. In addition to these development phases, the V- model also defines the procedure for quality assurance ( testing) phases.

This approach was first proposed by the US-based software engineer Barry Boehm in 1979 and is based on the waterfall model: The phase results are binding rules for the next deeper phase of the project. The left, leading down tree branch for the specification phase concludes with the realization phase. An extension towards the waterfall model are the time subsequent test phases, which are shown in the right, leading upward branch. Specifying the phases are opposite each test phase, resulting in the representation of a characteristic "V " results, which was also the name of the model. This comparison should lead to the highest possible test coverage, because the specifications of the respective stages of development are the basis for the tests (test cases ) in the corresponding test levels.

For V- model in general in the literature, the number of phases and their names are displayed differently, but always with a 1:1 comparison of design and test stages.

The general V- model is the basis of development standards, such as the V- model (Development Standard) of the public sector in Germany.