A core dump is a file that captures the memory of a running program at a specific point, usually when the program crashes or encounters a serious error. This file contains a snapshot of the program's state, including its variables, call stack, and other important data, which can be useful for debugging and diagnosing issues. Developers use core dumps to analyze what went wrong in the program, often with the help of debugging tools like GDB (GNU Debugger). By examining the core dump, they can identify bugs, memory leaks, or other problems that need to be fixed to improve the software's stability and performance.