tree is a unix tool that can be used to list directories and/or files or only directories in a structured format.
How to use tree
# syntax "options" and "directory" is optional
tree <options> <directory>
tree ./ # show all files/directory, starting from the current directory you're in.
tree -d ./ # show all directory, starting from the current directory you're in.
tree -a ./ # show all files, starting from the current directory you're in.
tree -F ./ # Appends '/', '=', '*', '@', '|' or '>' as per ls -F.
tree --inodes ./ # print inode number of each file