By default, each of your photo albums is visible to any other member. You can change that on an album-by-album basis. To do so, go to Account under the gear icon at the top right of any page, then select Privacy. You'll have the option to select who can view each of your albums: Public (everyone) or Only friends & communities.
Note: These settings only apply to photo albums posted on your profile. Your now and then profile photos, as well as other profile content such as your story, profile notes, etc. are visible to all other members.
