"Secret photos" is the option that allows you to see other members' locked pictures. You will recognize Secret photos by the icon saying 'Locked' instead of the actual photo. To see other members' Secret photos, click the "Unlock Secret photos" button on their profile or in your search results and then wait for them to accept your request. The "Show Secret photos to all" option is enabled by default in the "My Account" section on your profile. If you prefer not to show some of your photos to everyone at once, you can disable this option. Secret photos and 'For Friends Only' photos are not the same. 'For Friends Only' photos are available solely to your friends. Secret photos are available by request.