A software bug is an error in a computer program that causes it to behave unexpectedly, and these bugs can appear at any stage of the Software Development Life Cycle (SDLC). Although no software can be completely free of bugs, implementing effective management and testing practices can help minimize their impact. The Defect Life Cycle, or Bug Life Cycle, is a series of stages a bug undergoes from discovery to resolution, including states such as New, Assigned, Open, Deferred, Dropped, Duplicate, Fixed, Pending Retest, Retest, Reopen, Verified, and Closed. These stages help ensure that bugs are properly documented, assigned, and fixed, with variations like "Cannot be fixed" or "Need more information" arising in specific situations. Despite the inevitability of bugs, having a structured plan to address them is beneficial, with prevention being more effective than merely reducing their numbers. The insights are provided by Arnab Roy Chowdhury, a UI developer and blogging enthusiast with expertise in technical content.