When you enter Facebook sweepstakes, take quizzes, or even use a 'quick log-in with Facebook' option on another website, you give applications from companies outside of Facebook permission to access some of your Facebook information and to collect data about you.The data the apps collect can be used for marketing purposes, leading to more spam.If the company behind the app is not reliable, your private information can be used for even more nefarious purposes like harassing your friends or making you more vulnerable to hackers. To enter a giveaway, for example, you might be asked to give the app access to your profile information, your location, the ability to post updates on your wall, access to your list of friends, and more.

If you don't want to remove a Facebook application altogether, you can also protect your privacy by restricting or revoking its access to your personal information.

When you first agree to give access to a Facebook application, you might not have much control over what permissions you give it.

However, by clicking on the "Edit Settings" link next to the application's name in your privacy settings, you can see whether each type of permission is required or not.

For example, access to basic profile information might be required to use the Facebook application, but the right to post to your wall might not be.

That adds up to a lot of third parties having access to personal information.

To protect your privacy on Facebook, take the time to review the applications that have access to your Facebook account regularly, and to remove any applications that you no longer use (for example, when a giveaway has expired or when you have finished taking a quiz).

It only takes a few seconds to remove access from Facebook apps.

It's a smart idea to pick an easy-to-remember date, such as the first of every month, to review which apps have access and to remove them or limit their reach.

If a level of access is not required, you'll see the option to "remove" that access.