A runtime error that occurs when a program attempts to access memory that it's not allowed to access, causing the operating system to terminate the program for protection.
Segmentation comes from memory management where RAM is divided into segments (1960s). Fault is borrowed from geology, describing a break or error. The term reflects how the OS 'faults' or stops a program that violates memory boundaries.
It's like trying to walk into someone else's house without permission - the security system (operating system) immediately kicks you out to protect the neighborhood. This is actually your computer protecting itself from rogue programs!
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