How do I open a file?

The relationships files allow one to quickly navigate through the package without having to open up each part. If someone wanted to find all images that are referenced in a wordDocument, he or she wouldn't even need to open the wordDocument.xml part. Just open the relationships file and look for all relationships that are of type http://schemas.microsoft.com/office/2006/relationships/image. If you want to change this to point at a different image, you just edit the relationship, and don't need to modify the application level XML. This is especially useful for external relationships.