The System Development Life Cycle (SDLC) is a methodolgy and sequence that is used for designing and developing software applications. The steps or phases of the SDLC life cycle consists of things like planning, requirements, design, testing, and implementation.
Planning: The objective of this phase is to conduct a preliminary analysis, propose solutions, describe costs and benefits and recommendations.
Requirements: In this phase we define the business requirements, project goals and defined functions and operation of the application.
Design: In this phase, features and operations are architected in more detail, including screen layouts, business rules, process diagrams, pseudocode and other documentation.
Development: This is the coding process and where programmers are busy coding.
Testing: All the pieces of the application are tested. There are multiple levels of testing where an application is tested for bugs and interoperability. The testing phase includes things like test plans, unit testing, integration testing, and load testing.
Deployment: The software is installed and deployed on the production environment.