To deliver a bug-free or quality product we need to test it initially. Testing is nothing but verifying an application to check if the application is working as per the client requirements or not.

The developer thinks in the point of code and logic. There should be someone who could think like end users. And thus, tester comes into picture and testing is needed for sure.

When does the testing begin:

1. If the requirements are clear
2. If the requirements are understandable

When does the testing end:

Testing could be never ended up, it’s a continuous process. Even after the application delivery, the testing could still continue.

But we could stop testing by considering below parameters,
1.When all the customer requirements are implemented in the application and are tested and are working as well
2.When the QA(Quality Assurance) Metrics show 100% quality of the application
3.When Application is delivered to the end user and maintenance is done
4.When Application is bug-free

What is Requirement:

The requirement is the set of all the customer needs.

Testcase:

The test case is a series of simple steps that has to be done to check a particular functionality. Testcases describes test procedures, set of inputs, expected result, actual result, status(Whether it is new, fixed etc. state)

Below are the essential parts we need to test:

1. Check entire site if there are any grammatical errors
2. Fill out the forms with different combinations in positive and negative scenarios.
3. Whether the site compatible with all kind of operating systems, browsers etc.
4. Need to check site performance by navigating from one page to another page, by downloading any content from the site, image loading time.
5. We need to maintain user data securely.
6. All the menu navigations in the site and mobile linking's

Retesting:

We should test the application one more time after fixing major changes. If we got any issues while testing the app, we need to resolve those issues as soon as possible and after fixing the issue we need to test all the possible areas too. Because may be another issue raised by fixing one issue. It takes several rounds of testing to deliver/launch quality product/project.