In software development, what does 'debugging' refer to?

Debugging refers to the process of identifying, isolating, and correcting errors or bugs in the software code. This is a crucial aspect of software development because bugs can lead to incorrect functionality, crashes, or unexpected behavior in applications. During debugging, developers use various tools and techniques to trace the source of errors, assess the impact of the bugs, and implement fixes effectively. This might involve examining code logic, reviewing error messages, or using debuggers to step through code execution to understand how it operates in real-time.

The other choices illustrate different activities within software development but do not accurately capture the essence of debugging. Writing new code pertains to the initial creation of software, testing for performance is focused on ensuring the software runs efficiently under various conditions, and optimizing database queries is about improving the efficiency of data retrieval operations. These activities are vital to the development process but are distinct from the specific task of finding and fixing code-related issues, which is the core of debugging.