For example, I've been working a lot on these two directories in my pxeboot server ((The xxxx is just a placeholder)).
Typing those in each time, using tabs, and even using relative paths can be quite a pain in the butt. So I set two alias to get me back to those directories quickly after I wonder off and need to come back.
I added these two lines to my .bashrc file:
alias nn='cd /opt/xxxx/sources/linuxdistros/centos/x86_64/5.3/' alias oo='cd /opt/xxxx/sources/linuxdistros/centos/x86/4.4'
Then either source .bashrc, or logout and log back in. Now when I type "nn" or "oo" I get sent to those directories.