Compressor Job Chaining

I am studying Compressor 3 online and have run into the "job chaining" section.

Is there an easy description of what chaining's purpose is? I understand how to job chain, somewhat. The reason for using "job chaining" is confusing.

Thanks

Carl

Here is a hypothetical situation for you:

Say you have an HD Master that needs to be down-converted to an SD Master because your client has requested both HD and SD Masters. They also want from that SD Master a variety of outputs for DVD, Web, DVD-ROM. iPhone, etc. So instead of painstakingly creating all those SD media children from an HD master (basically spending a lot off time just tossing pixels away) you can Job Chain. First Job is the HD to SD down-convert, then make all the SD children form the newly created SD master, saving loads of time, all without having to sit by and babysit the process. With all that time you saved, you could bake a batch of cookies to send to all your favorite helpful folks on the Forums.

I hope that helps.

- Jackson