Shared albums are albums that you can set the privacy level for only certain people to view it. When you set the privacy level of an album to Custom, you will then have to choose who you want to view this album from your list of fans.
The shared album feature allows you to be selective of which fans or people can view it. This gives you more freedom and flexiblity to be yourself when you post.
The users of shared albums will see these posts in their timeline as normal, on your profile albums list and on the their shared albums tab.
You can manage users any time from the Edit option in the Album menu.