A "Segmentation Fault" is an error that occurs when a program tries to access a memory location that it is not allowed to use. This can happen if the program attempts to read or write to an area of memory that has not been allocated or is protected. It is a common issue in programming languages like C and C++, where developers manage memory manually. When a segmentation fault occurs, the operating system typically terminates the program to prevent it from causing further issues. Debugging tools can help identify the source of the fault, allowing developers to fix the code and ensure proper memory management.