What commands are used for navigating the filesystem?

Three commands cover navigation: pwd ("where am I?"), ls ("what's here?"), and cd ("take me there"). They map onto the three questions you ask constantly at the command line.

Because the shell has no visible "you are here" map, these are how you stay oriented. pwd prints your current location, ls shows the contents, cd moves you. A few cd shortcuts make movement quick:

cd        # straight to your home directory (cd ~ does the same)
cd -      # back to the *previous* directory you were in (toggle)
cd ..     # up one level
cd ../..  # up two levels

cd - is the hidden gem: it bounces you between two directories, so you can dart off to check something and snap back with one command.

The most-used ls options pack a lot of information:

ls -l    # long format: permissions, owner, size, date
ls -a    # include hidden dotfiles (.bashrc etc.)
ls -la   # both at once (very common)
ls -lh   # long format with human-readable sizes (4.0K, 2.3M)
ls -R    # recurse into subdirectories

Why -a matters: Linux hides any file whose name starts with ., and that's where all the per-user config lives. A directory that looks empty under plain ls may be full of dotfiles — ls -a is how you actually see what's there.

Tip: combine freely — ls -lha is a popular "show me everything, readably" default.