Now that we know different environment type classifications, let's look at how many environments you need for your project. 

The following screenshot shows a sample template that highlights different environments and sizing tiers you may need, depending on the project's complexity:

As shown in the preceding screenshot, the number of environments you need and sizing requirements typically depend on the complexity of the project. In a simple project, you can reuse one environment for multiple purposes.  For example, the test environment can be used for pre-production data migration, UAT, and training purposes during the different phases of the project. However, for a complex project, you should plan a separate environment for their purpose. 

Now, let's learn in the next section about the environments that are provided by Microsoft when you buy a Finance and Operations license.