This is your moment, you've decided to step up and make a job board for your local Drupal User Group. You spend some time thinking about everything you'll need, including the job listings themselves. You'll want to gather the standard info, like job title and job description, salary, experience, the works. When it comes to gathering company info, your instincts make you take a few extra moments to plan.
If you think about this from the perspective of the person posting 6 or 7 jobs, she would end up having to type (or at least copy and paste) the business' contact information each time. If you think about collecting 3 or 4 fields for each business, then that's about 20 extra form fields for the user to fill out. If she then decides to change the info, let's say she made a typo, she now must click through each edit screen 6 or 7 times. That amounts to hundreds of clicks and several hundred repeated keystrokes.
There must be a better way. A nodereference can help your users.
Once finished, you will have two nodes, one for a job and another for a company, and yet you will still display the information about the company inside the job listing.
By the end of this tutorial, you should understand what a nodereference is for, how to create and use one, and finally, how to use template files to theme the output of the nodereference and get the most out of the relationship.