When we work on an enterprise application, it is always useful to work in three separate environments:
Development environment
Staging environment
Production environment
Basically, an environment is a server configured for specific purposes (for example, to allow users to use a site or develop a new one).
You can also add more environments, such as Integration platform environment, where different teams would test if their code works fine together; usually, only these three are really needed.
This first environment is the one in which we will work. Usually, this environment has installed libraries useful for a development task, such as XDebug PHP module, but is totally useless, or even problematic, in a production server. For example, an enabled XDebug PHP module will slow down our production server, while adding overhead to every PHP execution. If you don't have a development server, this environment should be the computer where you create your whole application...