Difference Between Functional and Non functional Requirements

Functional vs Non Functional Requirements

The Key Difference Between Functional and Non functional Requirements is that Functional requirements describe what the system or software is supposed to do, whereas Non-Functional requirements describe how the system or software should perform.

Functional vs Non Functional Requirements
Functional vs Non Functional Requirements

Comparison Chart

  • Functional and Non functional Requirements both have different features and functionalities, here is a comparison of some key features between them.
Functional Requirements Non Functional Requirements
Functional requirement describes what a software system should do. Non-Functional requirements describe how the system or software should perform
Functional requirement is specified by User. Non-functional requirement is specified by technical persons.
Functional Requirements is mandatory. Non Functional Requirements is not mandatory.
Functional requirement is describing the behavior of the system as it relates to the system’s functionality. Non-functional requirement elaborates a performance characteristic of the system.
Verify the software’s functionality Verify the software’s performance
Functional testing such as API testing, system, integration Non-Functional testing such as usability, performance, stress, security, etc

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