The solution requirements describe the specific solution characteristics that the solution will need to possess to be able to meet the stakeholder requirements. These are the requirements that contain enough detail that a solution can be developed and implemented.

Solution requirements are divided into two categories:

• Functional requirements: These requirements describe the specific functionality that is required by the new solution – in other words, the functional requirements describe the capabilities that a solution must provide to its users. 

Although there are many acceptable functional requirement formulation approaches, an example of a functional requirement could be as follows:

"The teller scans barcodes to calculate the total grocery bill for the customer upon checkout."

You could phrase the same requirement as follows:

"As a teller, I scan barcodes to calculate the total grocery bill for a customer."

In this example, the functionality that is being described is about the ability to calculate the total grocery bill. In another example, you might have similar functional requirements for searching for products, printing receipts, or processing payments. It is about the functions the system provides to the end-user.

• Non-functional requirements or quality of service requirements: These types of requirements describe the characteristics that are expected of the solution. This is best described with a few different types of non-functional requirement categories.

Examples of non-functional requirements include requirements describing the performance requirements for a system, the transaction volume capability of a system, the security requirements of a system, and the usability of a system. There are many other non-functional requirements categories that can be used to describe the required characteristics of a solution.