The Linux directory that stores system configuration files is `/etc`.
The Filesystem Hierarchy Standard defines `/etc` as the location for host-specific, system-wide configuration files. These static settings control services, users, networking, authentication, and many other parts of a Linux installation. Familiar examples include `/etc/passwd` for account information, `/etc/hosts` for local hostname mappings, and service-specific subdirectories such as `/etc/ssh`.
The name historically meant “et cetera,” reflecting an early catch-all directory in Unix; later explanations such as “editable text configuration” are retrospective interpretations rather than the original meaning. The competing directories have different roles: `/usr` contains most userland programs and shared data, `/var` holds changing data such as logs and package databases, and `/opt` is intended for add-on application software. Configuration associated with software installed under `/opt` may be placed in `/etc/opt`, but the main system-wide configuration hierarchy remains `/etc`. Distribution practices vary in detail, yet this convention is fundamental across Linux systems.