Twitter subscribers don't join the global microblogging service to post private messages. They typically post their thoughts and observations to gain the widest possible visibility and exposure -- with two exceptions. Twitter's protected tweets and direct messages form two private ways to communicate within a social media site otherwise devoted to hearing and being heard. These special categories of subscriber accounts and messaging work within or alongside regular Twitter functions.

About Protected Accounts

You can protect a Twitter account so only your profile picture, bio, and lists of followed and follower accounts become visible to anyone except your followers. To see the tweets of a protected account, you must request permission and gain approval to become one of the account's followers. You won't even find protected tweets through Web searches. If a protected account replies to a tweet from or mentions someone who's not on its follower list, the reply or mention never materializes in the other party's timeline.

Viewing Direct Messages

Direct messages enable any Twitter subscriber to send a private tweet to one of his followers. You compose and view these messages in a separate part of the Twitter-client interface, accessible from your Web-based timeline or home page through an envelope-shaped icon on the menu bar. In October 2013, Twitter briefly experimented with enabling subscribers to DM any account they follow, even if the other party doesn't follow back, but one month later, the service rolled back this policy change.

Limitations and Exceptions

Twitter's built-in retweet mechanism places a one-click link below each message to enable subscribers to broadcast another user's post to a wider audience. If you're an authorized follower of a protected account, you can't use this feature to retweet the protected account's tweets; in fact, these links simply don't appear. The padlock icon that appears after the user's name on her profile page and with each tweet she posts signals her account's protected status. DMs' privacy doesn't make their content private if they include information or material that's otherwise accessible. For example, if you include a website link in a DM, the privacy of the message doesn't hide the page you reference.

Consequences and Considerations

Protected tweets make sense for people with a compelling reason to screen and limit who sees what they say. Unless a potential follower feels a strong motivation to communicate, the extra steps involved in gaining approval diminish many subscribers' enthusiasm for the task. Just as any subscriber can protect his account, however, he also can remove the protection and make his tweets visible. Once he does so, his formerly protected tweets also become public. DMs permanently remain private, but they include one feature that regular tweets lack. Either the person who posted a DM or its recipient can delete the message. Only the person who posts a regular public tweet can delete it.