Software testing is the process of verifying the working of the software system or application. In other words, it ensures the software application is bug-free and addresses the technical and user requirements. It not only focuses on finding bugs or errors in the software but also considers measures to enhance the software quality in terms of usability, accuracy, and efficiency.
Suppose you are building a software application that involves writing a bunch of codes and fixing bugs. These are part of the Software Development Life Cycle that developers and testers follow. However, it is their accountability to check or verify the code in line with the requirements and performance of the application.