The staged software development model is similar to the Prototype Model since the software is shown to the client in different successive stages of development. It differs in that the specifications are not known in detail at the beginning of the project and therefore are developed simultaneously with the different versions of the code.

The following phases can be distinguished:

These different phases are repeated at each stage of the design.

This model stipulates that the software will be developed in successive stages:.

1. Operational plan

Stage where the problem to be solved, the project goals, the quality goals are defined, and any restrictions applicable to the project are identified.

2. Requirements Specification

It allows us to deliver a high-level vision of the project, placing emphasis on the description of the problem from the point of view of clients and developers. The possibility of resource planning on a time scale is also considered.

3. Functional specification

Specifies the information on which the software to be developed will work.

4. Design

It allows you to describe how the system will satisfy the requirements. This stage often has different levels of detail. The highest levels of detail generally describe the components or modules that will make up the software to be produced. The lowest levels describe, in great detail, each module that the system will contain.

5. Implementation

This is where the software to be developed is coded. Depending on the size of the project, programming can be distributed among different programmers or groups of programmers. Each will focus on building and testing a piece of software, often a subsystem. Testing, in general, aims to ensure that all functions are correctly implemented within the system.

6. Integration

It is the phase where all independently coded subsystems come together. Each section is linked to another and then tested. This process is repeated until all modules have been added and the system is tested as a whole.

7. Validation and verification

Once the system has been integrated, this stage begins. It is where it is tested to verify that the system is consistent with the requirements definition and functional specification. On the other hand, verification consists of a series of activities that ensure that the software correctly implements a specific function. At the end of this stage, the system can now be installed in an operating environment.