What is the definition of 'bug' in software testing?

In software testing, a 'bug' is defined as a flaw in the software that produces an incorrect or unexpected result, or causes the software to behave incorrectly. This definition is important because it encapsulates the essence of what a bug is: any deviation from the intended functionality or output that can affect user experience, system stability, or overall application performance. Bugs can arise from various sources, such as coding mistakes, logical errors, or even issues with the software's design.

Identifying and fixing bugs is a critical part of the software development process, as they can lead to significant problems if left unresolved. By understanding that a bug is not just a minor issue or an isolated mistake, testers and developers can prioritize their efforts to ensure that software is functioning as intended and delivering the expected results to users.