What are different environments in a software development team and why do we need different environments???

There are mainly 4 different environments in a software development life cycle. Each of the environments is used by a different set of users and helps in maintaining a different codebase of the application. So, the changes made in one environment does not impact users of other environments for example:- Development team creates programs and execute unit tests in development environment while test team uses SIT environment to validate that the application is defect-free and all of this has no impact to the actual users of the application using a production environment whereas UAT environmentis for testing the software in user environment.

1. Development
2. SIT - System integration testing
3. UAT - User acceptance testing
4. Production

Source: Slideshare