The Software Development Life Cycle (SDLC) is a process used in the software industry to design, develop, and test high-quality software. It is a structured process that enables the production of high-quality, low-cost software in the shortest possible production time. The SDLC aims to produce a high-quality software that meets or exceeds customer expectations, reaches completion within times and cost estimates. The SDLC concept applies to a range of hardware and software configurations, as a system can be composed of hardware only, software only, or a combination of both. The SDLC involves several stages, which can vary depending on the methodology used, but typically include:

1. Requirement Analysis: In this stage, the requirements for the software are gathered and analyzed to determine what the software needs to do and how it will be used.

2. Design: In this stage, the software architecture is designed, and the software components are identified.

3. Development and Testing: In this stage, the software is developed, and testing is performed to ensure that it meets the requirements and is free of defects.

4. Implementation: In this stage, the software is deployed and made available for use.

5. Documentation: In this stage, the software is documented to provide users with instructions on how to use it and to provide developers with information on how it was developed.

6. Evaluation: In this stage, the software is evaluated to determine if it meets the requirements and if it is performing as expected.

Various SDLC methodologies have been created, such as waterfall, spiral, agile, rapid prototyping, incremental, and synchronize and stabilize. The SDLC is important because it helps ensure that the right people are involved in the right activities at the right times, and using a structured approach to developing software helps ensure that the project will be successful.