Twitter treats any tweet that starts with an @ symbol as a direct conversation with another user and treats those tweets as if they were to be private. Only the person that’s tweeting, the person being tweeted at, and those that follow both accounts will see the tweet and in their streams. This was huge. From the start of using Twitter, I was always nervous about tweeting @replies to people because I didn’t want to blast all of my followers with tweets they might not be interested in. Knowing that these @-reply tweets are kept out of the main feed made me feel much more comfortable with replying to people.