The difference between Functional and non functional testing

In any software development, there are different processes involved. Among them, one of the most important processes is testing. This is the process that assures the satisfaction of the customers. Also, there are standards and requirements for the software product and the quality analysis process that needs to confirm this stage as well. In testing there are two types, one is functional and the other is the non-functional testing.

Functional Testing
As the name suggests, every functionality of the software can be defined by using functional testing and it confirms with several other specifications required for the process. The functional is a type of black-box testing only and not about testing the code.

Every functionality of the system will is provided with the known input and verifies the output. Later, it finalizes the results by comparing the obtained results to the expected results. This can be done by some processes like interface, clients/ server application, security, database, and the functionality of the application that is considered under the testing. This test can be done manually or automated.

Non-Functional Testing
Non-functional testing is the type of testing in which only the non-functional part of the software application is tested that includes performance, reliability, usability, etc. This type of testing is performed particularly for enhancing the readiness of the system. Also, there are non-functional parts that will not be addressed by functional testing.

The Differences Between Functional and Non-Functional Testing
Although the functional and the non-functional testing perform their functions for delivering the quality software for the stakeholders and to enhance the quality of the software, there is a difference in the testing.

The functional system will identify how well the system can work but the non-functional will identify how the software responds. For example, if the functional testing will test the functionality of the input data, the non-functional testing will test how quick each document will be saved.

Functional testing will take care of the customer’s requirements, but the non-functional will be based on the expectations of the customers. Now, today's business shows a significant difference between the expectation and requirements of the clients. This can be resolved only with the help of non-functional testing.
Customer feedback has greater value for non-functional testing. Though the functional testing benefits mostly with the feedback, the non-functional testing gains more information with it. It is because it will allow the testers to know the customers’ expectations and the impacts on their products.
It is difficult to conduct a thorough and efficient non-functional testing process without appropriate tools. This is not a major issue in the case of functional testing as it can be done easily with manual testing as well.
The other major difference can be the nature of the requirements on which the tests are based. The functional requirements will mention the functionality that needs to be tested and the non-functionality will test how they will need to be tested. Also, the implementation of both the type of test will require tests performed in separate places. The functional requirements are defined in the system design; the non-functional requirements will be defined in the architecture of the system.
For an easy understanding of both the systems, you can go through a better example. Under functional testing, it is possible to test if providing the username and password on the log-in screen will allow the user to log in to the site. For the non-functional testing, you can check if the user will be able to log in to the site within 3 seconds by providing the username and password.

Conclusion
For any testing, non-functional testing is very important. The testing process cannot be completed without such a test. It is to ensure that the application or product behavior is acceptable and completely in line with requirements for the business.

Such non-functional testing will need strategizing and planning. If required, you can include some non-functional testing details in the overall test plan or alternatively devise a unique plan for it. In any condition, the final result will cover all the non-functional aspects of the comprehensive software concerns.