There are a number of methods for specifying which directory and file you are interested in. Pathnames (the directory specification) can be relative or absolute. Absolute pathnames begin with a slash, /, and start at the root directory. Successive directories down the path are also separated by a slash. In the previous paragraph I gave the absolute pathname of my home directory. Each subdirectory is a branch in the directory tree.
A relative pathname begins with the directory you are in (commonly referred to as working directory) and moves downward to a lower directory. Relative pathnames begin with the name of the first directory below the working directory. Each lower directory down the path should have a slash in front of it. Assuming I was in the /home directory, cernan/taylor would be the relative pathname to my home directory. A ``.'' indicates the working directory, while ``..'' indicates the directory one level up (known as the parent directory). If I were in my home directory, the relative pathname for the /home directory would be ../.. which says go to the ``grandparent'' directory two directories higher than you are now.