Why is software testing necessary?

Errors made by us, when executed can lead to software failures. Some errors and mistakes are minor but some are quite dangerous and require constant evaluation and monitoring. Therefore, it has become vital for software engineers to implement testing throughout the software, to ensure the efficiency of the developed software as well as to verify that no defects or bugs are left undetected, as they can hamper the intended quality, effectiveness, & performance of the software. Moreover, testing is a process that helps measure the quality of the software.