The audience selector lets you choose a specific audience when posting. Your options may include:

Public: When you share something with Public that means anyone including people off of Facebook can see it.

Friends (+ friends of anyone tagged): This option lets you post stuff to your friends on Facebook. If anyone else is tagged in a post, then the audience expands to also include the tagged person and their friends. If you don't want your photo or post to be visible to the friends of the people you tag, you can adjust this setting. Click the audience selector next to the story, select Custom, and uncheck the Friends of those tagged box.

Only Me: This option allows you to post stuff to your timeline that is visible only to you. Posts with the audience of Only Me will appear in your News Feed but not your friends' feeds. If you tag someone in an Only Me post, they will be able to see the post.

Custom: When you choose Custom, you can selectively share something with specific people, or hide it from specific people. You can also share with specific friend lists if you’ve set them up, such as Family or Best Friends, or hide posts from your Coworkers list. Custom also provides the option to share with groups or networks you belong to.