System Development Life Cycle (SDLC) - a systematic approach to problem solving, consists of several phases, each comprised of multiple steps:

1. The software concept - identifies and defines a need for the new system
2. A requirements analysis - analyzes the information needs of the end users
3. The architectural design - creates a blueprint for the design with the necessary specifications for the hardware, software, people and data resources
4. Coding and debugging - creates and programs the final system
5. System testing - evaluates the system's actual functionality in relation to expected or intended functionality.

For the reasons explained below a business may not use SDLC.

Criticism of SDLC
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Although the SDLC Model has been used extensively for many the years in the production of many quality systems, it is not without its problems. Recently it has come under attack, due to its rigid design and inflexible procedure. Criticisms fall into the following categories:
· Real projects rarely follow the sequential flow that the model proposes.
· At the beginning of most projects there is often a great deal of uncertainty about
requirements and goals, and it is therefore difficult for customers to identify these criteria on a detailed level. The model does not accommodate this natural uncertainty very well.
· Developing a system using the SDLC Model can be a long, painstaking process that does not yield a working version of the system until late in the process.

As customers demanded faster results, more involvement in the development process, and the inclusion of measures to determine risks and effectiveness, the methods for developing systems changed. In addition, the software and hardware tools used in the industry changed (and continue to change) substantially. Faster networks and hardware supported the use of smarter and faster operating systems that paved the way for new languages and databases, and applications that were far more powerful than any predecessors. These rapid and numerous changes in the system development environment simultaneously spawned the development of more practical new Process Models and the demise of older models that were no
longer useful. Here are some of the new Process Models:
- Iterative Development,
- Prototyping,
- Rapid Application Development,
- Exploratory Model,
- Spiral Model,
- Reuse Model