How can I list everything below a directory?

In order to see everything underneath a directory, no matter how deeply nested it is, you can give ls the flag -R (which means "recursive"). If you use ls -R in your home directory, you will see something like this:

backup          course.txt      people          seasonal

./backup:

./people:
agarwal.txt

./seasonal:
autumn.csv      spring.csv      summer.csv      winter.csv

This shows every file and directory in the current level, then everything in each sub-directory, and so on.