Twitter is, in many ways, the most self-indulgently pointless of social media tools. It's a 140-character micro-blogging service that you use to tell your friends (and the world, if you want) about what you're up to. The cliched Twitter message is a report about what you are having for breakfast or a groan about how your computer is failing to boot sufficiently quickly.
For a long time, Twitter grew steadily and quietly. While it experienced big growth, it still inhabited a geeky underworld. Your mum might have been on Facebook, but only your hardcore gaming nephew was on Twitter.
You might have come across it occasionally as it surfaced in news reports - breaking news often comes through Twitter these days - but that's often because social media nerds use these stories to trumpet the way "citizen journalists" and Twitter have trumped the mainstream media.
Then, all of a sudden, in the last few weeks, Twitter has poked its nose properly into popular consciousness.
It probably began when Stephen Fry started twittering a few months back and rapidly acquired thousands of followers. This was partly because Fry was a bona fide celebrity who people could interact with directly (until he was overwhelmed), but partly because he was good at using it. Fry is a deeply geeky man and knows the cultural references that the digital crowd dig.
He was an instant Twitter hit. But if it had just been him, it might have petered out at that point. Instead, along came Jonathan Ross, known as "Wossy", who has acted as a sort of gateway drug for celebrities on Twitter. Ross discovered it while on enforced leave of absence from proper media and took to it immediately. Twitter allowed him to "broadcast" (which he clearly has an urge to do), but in a strangely hybrid public/private way.
Since Fry talked about Twitter as a guest on Ross's comeback show, every minor celebrity you can think of has been twittering away to more or less acclaim. Now huge numbers of people, businesses and brands are pouring on to Twitter, which is causing resentment and grumbling among the old-timers, as though they are residents of a newly fashionable village.
This should probably be a chastening thought for many social media advocates, because whatever we digitalistas might think, it took Friday night telly to validate Twitter's existence for many. Twitter was all-atwitter about that very fact, giddy with excitement about being on the telly. The new media are still delighted when they break through on to the old. Just don't tell Thinkbox I said that.