1. Bag contents are stored with a FAQ, mirrored with a FAQ, and when a FAQ is copied off to a CD or some other distribution mechanism, the bags go with it. So use a bag instead of an http: or other generic link when you want to ensure that the stored data itself, not just a reference to it, becomes part of the FAQ.

2. Bags are the only way to put inline images (such as diagrams) into a FAQ. This is partly because bags maintain referential integrity (item 1), and partly because it gives administrators tighter control over who can add inline images to a FAQ (to avoid undesired skankiness).

When you upload a new bag, you specify the text part it gets added to. After the upload, the text part will include a "baglink," an icon and link to the contents of the uploaded data. If the bag is an image, you can edit the text and change the "baglink" to "baginline", and the image will appear in-line in the text body.

Because bags allow arbitrary file content to be stored with a FAQ, administrators are likely to restrict more tightly who can add a bag to a FAQ. If you have something to contribute and you don't have the permission to do so, contact the administrator of your FAQ.