It is common practice to have a number of stages environments for software at different stage sof the lifecycle and stability. Each staging environment is used for a specific set of purposes by those users. The number of environments varies between projects, typically the main controlling factor is cost. More levels are expensive but may help with larger team sizes. Cloud hosting allows the ability to dynamically create and decommission environments when required to allow cost savings.
The project should be clear who is responsible for the various staging environments including: