Business analysis glossary
FRD (Functional Requirements Document)
What it is
An FRD describes in detail how a system must behave to satisfy the business requirements. It lists functions, rules, screens, inputs, outputs and error handling, and is written for the delivery team. It is often organised by feature or process and uses numbered statements, screen sketches and tables so each rule can be traced and tested.
Why it matters
It turns business intent into specific behaviour that can be built and tested. It also provides the detailed list that test cases are checked against. Without this detail, different developers may implement the same sentence in different ways, and the differences are only discovered in testing.
Example
Where the Kestrel Bank BRD says, "Customers can move money between accounts," the FRD specifies the transfer form fields, daily limit rules, validation messages and what is written to the audit log. Each of those details becomes something a developer implements and a tester checks, which is why the FRD tends to be long and precise.