Software development life cycle models (SDLC models)

- - Software company adopts the best-suited software development life cycle models, which suits the team members and the software product
  - SDLC models specify the various stages of the process and the order in which they are carried out.
  - Different software life cycle models models need different approaches to test the Product.
  - Each development activity should have a corresponding test activity.
  - Any software development process is divided into several logical stages that allow a software development company to organize its work efficiently in order to build a required software product within a specific time frame and budget.

There are various Software development life cycle models (SDLC models) as follows:

Waterfall Model

- - SDLC Waterfall Model is a traditional model and It is also referred as a linear-sequential life cycle model.
  - Waterfall Model is a sequential design process, often used in SDLC, in which the progress is seen as flowing steadily downwards (like a waterfall), through the different phases.
  - At the end of each phase, a review takes place to determine if the project is on the right path.

- - V Model can also be called as Sequential Development Model .
  - V – Model came up in order to overcome the drawback of waterfall Model .
  - In V-Model process executes in a sequential manner in V-shape.
  - V – Model is based on the association of a testing phase for each corresponding development stage.

- - Iterative Model is a process of defining requirements, designing, building and testing a system, completed as a series of shorter development cycles.
  - Software development process where requirements are divided into several stand-alone software development modules.

The Spiral Model includes iterative and prototype approach.

Spiral Model has four phases:

- - In Agile, a product is broken into small incremental builds.
  - Agile model quickly delivers a working product and is considered a very realistic development approach
  - The Agile model produces ongoing releases, each with small, incremental changes from the previous release.
  - At each iteration, the product is tested.

- - Big Bang model follows no specific process, and very little time is spent on planning.
  - Big Bang Model is one of the SDLC methodologies typically used for small projects with only one or two software engineers.
  - Big Bang is not recommended for large or complex projects, as it’s a high-risk model