The linux folder structure:
/bin essential command binaries, e.g cat, ls, cp
/sbin system binaries
/dev device files, e.g. /dev/sda1 points to the first (a) hard drive and 1st partition
/etc configuration files, all sorts of xxx.conf
/home home folder for users
/lib libraries essential for the binaries in /bin and /sbin
/usr secondary hierarchy for read-only user data; contains the majority of user utilities and apps
/var variable files, which is expected to continually change during normal operations, such as logs, spool files.
/tmp temporay files, not preserved after reboot, /var/tmp keeps preserved temporary files, such as web logs
/media mount points for removeable mdeida e.g cd rom
/mnt temporaily mounted file systems
/opt optional application software packages
/run run time variable data
/srv site specific data served by this system, such as data and scripts for web servers, data offered by ftp, etc.
/sys contains information about devices, drivers and some kernel features
Below is from bytebytego: