PPA - personal package archives
FHS - Filesystem Hierarchy Standard
/bin - binaries (programs/applications)
/sbin - system utils
/boot - everything OS needs to boot (do not touch it!)
/dev - devices (accessed by apps and drivers, not user)
/etc - here all the system-wide configs are stored
/lib, /lib32, /lib64 - are used by apps to performe some functions
/mnt - mounted devices
/media - automatically mounted media devices (non-standard)
/opt - usually manually installed software
/proc - pseudofiles about processes and resources
/run - has a tempfs filesystem (it runs everything in RAM, volatile)
/snap - used by Ubuntu
/srv - here services data is stored.
/sys - relates to kernel and is volatile.
/tmp - where apps data is saved temporarily during a session.
/usr - applications installed by the users.
/var - files which are expected to grow in size.
/home - users' settings and files.
- KDE
- LXQt
- XFCE
- Deepin
- Pantheon
- Budgie