$songs{"artistname"}->{"albumname"}->{"songname"}
#[----] 
# %songs is a hash

#[------------------]
# each value in %songs is a reference, to a hash or "hashref".

#[--------------------]
# the "->" dereferences, so we've got a hash to look up
# "albumname" in.

#[---------------------------------]
# the look up in the inner hash returns another hashref

#[-----------------------------------]
# so we dereference again, and we're dealing with another 
# hash...

#[----------------------------------------------]
# ...in which we look up "songname", getting whatever.