I noticed some Twitter correspondents prefixing their messages with “.@username” rather than plain “@username”, and having been unable to find an explanation online anywhere, did the sensible thing and asked via Twitter…
I got several responses, which mostly tallied with each other (!), and with any luck I have worked out what the deal is. The only clear way I could think of to express it was (and Eve will be so happy)… a Venn diagram. Here you go.
D username: visible only to the sender and recipient;
.@username: visible to the sender, sender’s followers and the recipient;
@username: visible to the sender, recipient, and the intersection of their followers.
[Post updated, 16/3/2010]
A further note: as usefully pointed out by NishantK (see comments below), unless you have set your twitter stream to be private and non-searchable, of the three types of message above, only D(irect) messages do not appear in your profile page and search results.
In general, I still have two issues with this at the design level:
1 – When a humble full stop can make such a subtle syntactical difference, is it any wonder we find it hard to grasp how to manage our online personas effectively?
2 – I started out by being frustrated at why searching for “.@” didn’t produce any useful help with definitions; I graduated to exasperation when I learned that the “.” is actually arbitrary, and any other character would have the same effect. Is it just me, or is that really daft? It means there is, essentially, no practical way either to index or to search for information about a Twitter function which makes a difference…
I spent some time trying to think of a good word for “arbitrary, un-documentable feature” – but the only one I could come up with was “bug”.