When Sharing an album with others, there are three security options available:

1. Public - If you make the album public, then anyone who knows the Collaboration ID can access it without any other piece of information. 
2. Password - If you protect the album with a password, the user must provide it to gain access to your album.
3. Email List - If you protect you album via an email list, a user must provide an approved email address in order to access your album.

Therefore, a user must know the Collaboration ID and possibly one more piece of information to view your album.  Remember, unless you give someone your Collaboration ID, no one will know that it exists. 

When you send an email Share invitation to others, in your message you can tell them the requirements to access your album.

You can change the Security option for your album at any time.  If you do this, it may prevent friends from accessing your album in the future.

We only send the Collaboration ID to other users when you are Sharing an album with them. Your photos and information always remain private with us.  We respect your privacy.