Twitter allows you to share what you are doing at any given point during the day with anyone following you or the public.  Users can actually search for keywords or hash tags to find followers who share interests or viewpoints.  The only way you are included in those search results is if your Twitter profile is public.  If it is, your tweets are actually recorded as part of Twitter's public timeline and can be viewed by anybody who wants to read through them.

If you are a private person or want to limit you is following you, you can do this is one of two ways. First, you can make your Twitter private. This means that nobody publically can see your tweets unless you allow them to follow you. You will be excluded from the Twitter public timeline and you will have to approve those who can see your status updates.

In order to make your Twitter private, you want to head to Settings. Under the Account options, the default tab that opens when you click on Settings, go down to the bottom and you will see a little checkbox. It should say protect my updates. Check that box, hit the Save button and let the page refresh. Certain tweets that were public before may still be viewable to the public but everything else from that point on will be protected from prying eyes.

Next, you decide who follows you. Even if you follow someone, say a celebrity like Ashton Kutcher or Wil Wheaton, you do not have to let them follow you back if they send you a request. This means you can view their tweets but they cannot view yours. This may work well if your Twitter username gets around to family, friends or coworkers you do not want to know what is going on with you during the day.

Before you open a Twitter account, you should decide if you want it to be public or private.  Depending on the situation, a private account might be for the best.  Cases of users being fired for disparaging remarks against employers, significant others finding out something they should not have or even a parent reading about their child drinking have happened because of Twitter.  Make sure you are prepared for someone finding out about your goings on when signing up for the service and decide if going private is the safest option to safeguard your tweets.