What is the difference between Usability testing & Functional testing

In a simple terms, 

 

Hai Sir,

Functional testing is carried out to ensure that the product behaves according to the functional requirements without taking design principles into consideration. This entails a series of tests which perform a feature-by-feature validation of behavior, using a wide range of normal and erroneous input data. In contrast, usability testing focuses on customer acceptance and how well the customer can use the product to complete the required task. Usability testing investigates all aspects of the usability of a product, including overall structure, navigational flow, layout of elements on a page, clarity of content, and overall behavior. 

 

usability testing needs to come after functional testing, once functional problems have been fixed. Performing usability testing on functionally-flawed products only unearths functional problems, which leads to frustration for the participants who are struggling with bugs when trying to complete a task. It hinders the participants, it negatively influences their perception (and hence their feedback), and it invalidates the usability aspect of the results. 

 

Functionality testing confirms whether something works. Usability testing confirms whether it works well for users.Functional Testing belongs to Quality Assurance where Black Box/White Box testings are done on the applications to ensure 100% working of all functionalities.

You can solve a problem in many ways. All of them can be functionally sufficient (i.e. "user is able to add a new account number") but very few of them will be truly usable (i.e. "user is able to perform the task without looking in the manual").Usability Testing deals with testing the application with real-time end users to understand if it really solves their problems with ease of use, minimal interactions and intuitive interface.