Bugs are often invincible during development, especially in large projects when multiple sub-teams of developers are working on development of different sub-modules of the project. The software developed (or during development) will always appear innocent and bug-free to the team of developers. It is the tester’s tough task to puncture the software and find out the hidden bugs. If bugs during testing phase are not found completely, it may lead to disastrous consequences, depending on the severity of unfound bugs. That is why, for developers and testers it is very important to understand the complete flow, sequence, modules, sub-modules, functional sequence to build accurately by developers and verification by testers.
Testers have to exercise the testing process and they have to ensure that they are following the right process to identify as many bugs as possible.