— Newt Gingrich (@newtgingrich) November 23, 2011
If you’ve noticed users putting periods at the beginning of their tweets, it’s probably not a typo. In order to clean up users’ timelines, Twitter changed the way @mentions enter streams. Imagine a tweet is sent by @UserOne, and begins with the text “@UserTwo.” Only users who follow both @UserOne and @UserTwo will see that message.
This is great for replying to other users, since you don’t flood all your followers’ timelines while having semi-private conversations. Yet sometimes you will want to begin a tweet with somebody’s name when you are not replying to them. Perhaps you are just talking about them. In this case, the convention is to put a period before the @ symbol. This will prevent Twitter from seeing your tweet as a reply, and will place your message in all of your followers’ timelines.
Some users are not satisfied with this solution, since not everyone knows this trick and they will think your period is a sloppy mistake. If you subscribe to this argument, simply place another word before the person’s name you are referencing. This is easy enough when talking about candidates, as you can usually provide their title. For instance, “Gov.”, “Sen.”, or “Rep.” before their name uses only a few extra characters while solving the problem.
Whatever you do, don’t start a tweet with an @mention if you want all of your followers to see it. We’ve found tweets beginning with the character “.@” get 11 times the average retweet count of tweets with just “@” at the start.