This is so obvious, yet little known – and although Mark Suster warned us all right here at CloudAve, I keep on falling in the trap. Just today as I wanted to announce yet another great post by Mark, I tweeted this:
@msuster discusses how the Ice Age is thawing for Venture Capital
Big mistake. Had I written “great discussion by @msuster”, a lot more people would have seen it. Why? I’ll just quote the key chapter from Mark’s original tutorial:
This is important … If you send somebody a message and you START it with an @name then the only people who will see your message are people who follow you and people who follow the person you replied to. Most people don’t seem to know this. For example, if you follow me but not @deblanda an I send her a message starting with an @ then you won’t see it at all. Anyone who follows both of us will see the message. If you precede the message by anything, even a dash and a space like, “- @deblanda nice to see you” then everybody will see it.
When does this come into play? Sometimes I’ll see people who want to make people aware of a blog posting. They’ll say “@msuster provides great insight into VC valuation discussions – see http://bit.ly/C5t6O” . They might have 2,000 followers. I have 1,200. Only the small subset who follow both of us, say 100, will see the message.
So if you’re really responding to somebody and you don’t want all your followers to see it (but you don’t necessarily want to send a private message via DM or you can’t because they don’t follow you) then start with an @. Otherwise make sure it has text in front of it.

Good post, but let me add three more things.
This can also work in your favor. For example, I am a bit more flippant with @replies – particularly to people that don’t have tons of followers.
This feature also can serve as a nice filter. I used to follow a pair of folks that tweeted all the time to each other. I also noticed that if one tweeted something profound, the other always retweeted it. So now I only follow one. Improved signal to noise ratio.
Lastly, it isn’t always true. Some twitter clients (HootSuite) follows the public stream instead of your personal stream. So if you use Hootsuite or PeopleBrowsr @replies are not filtered differently at all.
Dave M – (pindropsoup)
This will change when the new Streaming API from Twitter gets adopted by more clients.
Clients using this will get all tweets from, and tweets in reply to a User they’re following.
So, if you follow @a and @b, you will see all tweets from @a and @b, PLUS replies TO @a and @b
If you’re an old-school Twitter user, you’ll remember the “With Friends” stream you used to see on someone’s profile page – that brings this functionality back if clients support it.
It also lets clients deliver the old style “see all tweets from anyone you follow” setting that Twitter removed.
I tweeted on it some on my blog.