Facebook users have gotten used to changes to the social media giant’s privacy policy, which it tellingly refers to as its “data use” policy. Taking effect January 1, the updated rules clarify what Facebook considers public data — that is, information over which the company assumes control for its own purposes, such as advertising and market research.

The social network mainly has rejiggered its definition of what makes your information “public” in the first place, mostly to make it easier to understand.

The new language reads:

Public information is any information you share with a public audience, as well as information in your Public Profile, or content you share on a Facebook Page or another public forum.

Facebook defines “public” as the information you gave the company when you became a user, such as your name, gender, school, workplace, language, age and country. Further, you make information public when you share it and post it to Public (versus only to Friends).

Finally, if you share information with someone who chooses to make it public, it becomes public information, as do any of your comments on the Public posts of others.

In some cases, Facebook warns, you won’t see a way to choose between Public and restricted groups, in which case the post is by default public. In Facebook’s words: “If you share something and you don’t see an audience selector or another privacy setting, that information is also public."

All of this public data is fodder for Graph Search, a search engine native to Facebook that can also be seen outside of Facebook — a point that gets by many Facebook users. Facebook wants as many people as possible to view your content. Graph Search pushes social content (posts, photos of people who are tagged, etc.) into a searchable database that is expected to eventually rival Google in its reach.

In sum, unless you make a post visible to “Only Me” (negating the point of using a social network in the first place), nearly anything you post is likely to be visible to someone and maybe to people you don’t know.

It pays to keep in mind these four major points. Public information (as defined by Facebook) can:

●Be associated with you, even off Facebook

●Show up when someone does a search on Facebook or on another search engine

●Be accessible to Facebook-integrated games, applications and websites you and your friends use

●Be accessible to anyone who uses our APIs, such as our Graph API

An API (application program interface) is the code that allows different platforms on the Internet to interact. For example, an API allows your score on a game such as Candy Crush to automatically post to your Facebook Timeline. In effect, all of your public data is fair game for similar use.

A little bit of sugar helps the medicine go down, so Facebook has introduced a new tool that explains privacy information in a more user-friendly format. Called Privacy Basics, the presentation amounts to a highly stylized slideshow and frequently-asked-questions page that you advance at your own pace.

The Privacy Basics tool covers three main topics: What Others See About You, How Others Interact With You and What You See. From there, you can skip ahead to specific concerns, such how to choose to make a post public or visible only to a small group.

If you want to dig deep into the Data Policy, it’s posted as a link on the Privacy Basics page. The information is presented in a similar, reader-friendly layout and leads to eight subcategories, including topics such as What Kinds of Information Do We Collect and How Do We Use This Information.

Facebook, in an email to its users, suggests that people avail themselves of the Privacy Checkup tool. Find it under the lock icon on the far right of the blue command bar at the top of each page. (You need to be logged in.) Click on the lock, then choose Privacy Checkup. From there, you get a guided tour of all the privacy choices you can make and what each choice means, as well as your current settings. 

Greg writes about personal finance, business and technology. His work has appeared in Businessweek, Newsweek, Forbes, Bankrate and a variety of trade ​publications.

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