Once the requirements are identified and categorized into functional and nonfunctional requirements, they then need to be prioritized according to their importance in the application. If this prioritization is not performed, it will lead to increased costs of development, delayed deadlines, and reduced productivity in the organization. Broadly, we can classify the requirements under the following categories:

• Must have: These are those requirements that are critical to the success of the application and that must be present in the application when it ships.
• Should have: These are those requirements that will enhance the functionality of the application but that need some further discussion about whether they should be added to the application.
• Could have: These are those requirements that are mostly enhancements, and the presence or absence of which won't affect the functionality of the application. These requirements can be taken care of in later updates to the application.
• Wish list: These are those requirements that are considered features that can be added at some later point in time, but which are not mission critical to the application. These features can be reviewed later for inclusion in the application update cycle.