Public and Unlisted Galleries
Click on Public Gallery or Unlisted Gallery on the My Photos tab to find a single, unchanging URL to share all of your albums with friends and family.
People who visit your public gallery URL - picasaweb.google.com/username - can view all of your public albums, plus any albums that you've explicitly shared with them.
People who visit your unlisted gallery URL will see all of your public albums, all albums set to a visibility of 'Limited, anyone with the link,' as well as any albums that you've explicitly shared with them. This gallery includes a unique authorization key in the web address; the key is a combination of letters and numbers that make the address difficult to guess.
Tip: If you've shared your Unlisted Gallery but now wish to revoke access and reset your unique URL, you can manually generate a new authorization key at any time.