V模型是软件测试过程中最重要的模型。它也被称为验证和验证模型。它是由已故的 Paul Rook 在 1980 年代引入的。 V 模型是一个顺序过程，其中只有在当前阶段完成后才开始下一阶段。在此模型中，当台阶向上弯曲时，台阶不会以线性方式移动。
它类似于瀑布模型，因为我们从左到右遵循 V 模型，并遵循流程执行的顺序路径，就像在瀑布模型中一样。在瀑布模型中，遵循需求、设计、实现、验证和最终维护的步骤.同样，在V-model中遵循相同的步骤。所以我们可以说V模型是瀑布模型的替代品。
V模型和瀑布模型的区别：
除此之外，v-model 是瀑布模型的替代品。下面给出了这两种模型之间的一些差异。
| Waterfall model | V-model | ||
|---|---|---|---|
| The cost of Waterfall model is low. | V-model is expensive. | ||
| Simplicity of Waterfall model is simple. | Simplicity of V-model is Intermediate. | ||
| Flexibility of Waterfall model is Rigid. | Flexibility of V-model is Little flexible. | ||
| Waterfall model is a sequential execution process. | It is also a sequential execution process. | ||
| Waterfall model’s steps move in a linear way. | V-model’s steps don’t move in linear way. | Re-usability of Waterfall model is Limited. | V-model can be Re-use for some extent. |
| User involvement in Waterfall model is only in beginning. | User involvement in V-model is also only in beginning. | ||
| In Waterfall model testing activities start after the development activities are over. | In V-model testing activities start with the first stage. | ||
| Guarantee of success through Waterfall model is low. | Guarantee of success through V-model is high. | ||
| Waterfall model is a continuous process. | V-model is a simultaneous process. | ||
| Software made using Waterfall model, the number of defects are less in comparison of software made using V-model. | Software made using V-model, the number of defects are greater in comparison of software made using Waterfall model. | ||
| Requirement specification in Waterfall model is necessary in beginning. | Requirement specification in V-model is also necessary in beginning. | ||
| Waterfall model is less used now-a-days in software engineering. | V-model is widely used in software engineering. |