At the time of testing web based applications and client server applications, what you absorbed as a tester?

What are the categories of defects?

In customer details form having fields like customer name, customer address. After completion of this module, client raise the change as insert the two radio buttons after customer address. How you can check as a tester?

Explain the PDCA cycle.

What is the document needed to create a test case? How you tell it is test case?

Can you explain the elementary process?