Technical Analysys of Linux Distributions FileSystem Hierarchy
The location of systems files (binaries, configurations, logs, devices, docs...) are typically a nightmare for a junior operator handling with Unix dialects.
There are Unix standards, there's a Filesystem Hierarchy Standard, there's the distro maintainer's choice but, most of all you have tools useful to locate files positions: which, locate, whereis, whatis, apropos, find...
In the apparent chaos of nested directories there's still coherence and login:
/bin Essential user command binaries (for use by all users)
/boot Static files of the boot loader
/dev Device files
/etc Host-specific system configuration
/home User home directories (optional)
/lib Essential shared libraries and kernel modules
/media Mount point for removeable media
/mnt Mount point for a temporarily mounted filesystem
/opt Add-on application software packages
/root Home directory for the root user (optional)
/sbin System binaries
/srv Data for services provided by this system
/tmp Temporary files
/proc Kernel and process information virtual filesystem
/var Variable files that change their size
/usr Users commands and tools
/var/account Process accounting logs (optional)
/var/cache Application cache data
/var/crash System crash dumps (optional)
/var/lib Variable state information
/var/lock Lock files
/var/log Log files and directories
/var/mail User mailbox files (optional)
/var/opt Variable data for /opt
/var/run Run-time variable data
/var/spool Application spool data
/var/tmp Temporary files preserved between system reboots
/usr/X11R6 X Window System, Version 11 Release 6 (optional)
/usr/bin Most user commands
/usr/include Directory for standard include files
/usr/lib Libraries for programming and packages
/usr/local Local hierarchy
/usr/sbin Non-essential standard system binaries
/usr/share Architecture-independent data
/usr/src Source code (optional)