The author of an album or document can invite to view via the built-in e-mail message service. At this moment, a letter is sent; a user record is created with the specified e-mail address. In this case, the invited user also has access to the album or document.
If the user invited by e-mail has his own Photo-Pick account, this album will be displayed in his/her account too. The invited user can delete this album, but the album will not be deleted from the author's account.
The invited user can view the album and select images, but cannot delete the album or images. Also has no editing access.
For example, this is represented in the author's account:
This is how it appears in the invitee's account: