What error common on older systems occurs when a program tries writing to a protected area of memory?

The error that commonly occurs on older systems when a program attempts to write to a protected area of memory is known as a "segmentation fault" or "segfault." This happens when the program tries to access memory that it is not allowed to, usually due to improper memory management or bugs in the code. The operating system then terminates the program to prevent corruption of other processes or the system itself. Segmentation faults are often indicative of issues such as buffer overflows or dereferencing null pointers.