What is the difference between public and protected Tweets?
When you sign up for Twitter, you have the option to keep your Tweets public (the default account setting) or to protect your Tweets.
Accounts with protected Tweets require manual approval of each and every person who may view that account's Tweets.
Who can see my Tweets?
Public Tweets (the default setting) are visible to anyone, whether or not they have a Twitter account.
Protected Tweets may only be visible to your approved Twitter followers.
Note: If you at one time had public Tweets, those Tweets will always be public and searchable, even after you change your settings to protected; Only Tweets made after updating your settings will be protected. Also, unprotecting your Tweets will cause any previously protected Tweets to be made public.
Why would I protect my Tweets?
If you want to control who sees your updates, you may choose to protect your Tweets. You can always change your mind and make them public later.
When you protect your Tweets, the following restrictions are put in place:
People will have to request to follow you; each follow request will need approval. Learn more.
Your Tweets will only be visible to users you've approved.
Other users will not be able to retweet your Tweets. Learn more.
Protected Tweets will not appear in Twitter search or Google search.
@Replies you send to people who aren't following you will not be seen by those users (because you have not given them permission to see your Tweets).