FSD
Functional Specification Document
A document describing how a system should behave to meet agreed requirements.
Plain English
What the feature should do in detail.
In context
An FSD records functional flows, rules, inputs, outputs, and exceptions so implementation and testing can align.
Example
“The QA engineer used the FSD to design test scenarios.”
When you'll hear this
- solution design
- development
- QA testing
Common misunderstanding
An FSD describes behavior and is not always a complete technical implementation design.
Commonly used by
Related terms
Updated: 2026-09-22
