The Filesystem Hierarchy

Filesystem Hierarchy Standard (FHS)

PathPurpose
/Root of everything
/bin, /sbinEssential (system) binaries
/etcSystem configuration
/homeUser home directories
/varVariable data - logs, spool, caches
/tmpTemporary files (often cleared on boot)
/usrUser programs & libraries
/optOptional/3rd-party software
/proc, /sysVirtual kernel filesystems
/devDevice files
/bootKernel + bootloader
/mnt, /mediaMount points for removable/temp media
Exam tip: Logs go in /var/log. Configuration is in /etc. Never assume - memorising the FHS earns easy exam points.