/usr/bin : The binary path (symlinks: /bin /sbin)
/usr/lib : The library path (symlinks: /lib /lib64)
- Includes Python in, because many programs depend on Python runtime; in /usr/lib/python3
- Includes C/C++ Libraries in /usr/lib/gcc/<arch-kernel-libc>
- The root folder includes the C shared libraries
- Subfolders include package specific libraries, like Python, GCC, etc.
- Some applications (especially in /usr/local/lib) put files in the root folder too
/usr/lib32 : The multilib library path (symlinks: /lib32)
/boot : The boot files - EFI and GRUB
/dev : A ton of interfaces
- ??
/etc : Configurations
- Commonplace files include
  - hosts : Stores system host name
  - passwd : Stores user ID mappings
  - shadow : Stores user passwords
  - sudoers : Stores sudo configuration
  - hostname : Stores FQDN and partial hostname mappings to IPs, aside from DNS
  - resolv.conf : Stores DNS Resolver configuration
  - nsswitch.conf : Sets the order of host resolution by system library functions
/home/username : User home directory
- Stores user specific software configurations in .config and in the root folder
- Stores local software files in .local, but in a more casual style compared to /usr/local
- Stores software cache in .cache and in the root folder
- Flatpak uses .var folder to store user specific app installations
- Commonplace files include
  - X11 Related: .XAuthority, .xprofile, .xinitrc
  - Bash Related: .bashrc, .bash_history, .bash_profile, .bash_logout
  - Git Config: .gitconfig
  - Miscellaneous: .python_history
  - I don't know what: .inputrc, .lesshst, .gtkrc-2.0, .profile, .wget-hsts
/proc : A ton of interfaces
- ??
/root : Root home directory
/sys : A ton of interfaces
- ??
/run : A ton of runtime interfaces
- ??
Empty standard directories : /media /mnt /opt /srv
/tmp : Temporary directory
Other /usr Subdirectories:
- /usr/include
- /usr/libexec
- /usr/local : The manual installations as opposed to package manager installations
  - Has /usr/local/bin, /usr/local/lib, /usr/local/include and /usr/local/share
- /usr/share : Shared assets
  - Includes fonts, applications, icons, ...
- /usr/src : Empty folder
/var : A ton of runtime files
- ??

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