Twitter’s rise to global popularity has been pretty astonishing. It wasn’t too long ago that a tweet was little more than something we would wake up to on a summer’s morning, but now it carries with it a whole new meaning thanks to Jack Dorsey who turned it into the world’s biggest social networking and micro-blogging phenomenon, the users of which are now sending, on average, 50 million tweets a day.

However, growth in the micro-blogging service’s number of users peaked at nearly 20 percent last April, but had dropped down to 0.15 percent in December 2009, according to a new study by Barracuda Networks.

The study looked at around 19 million Twitter accounts in order to figure out how people are using Twitter. It started with one assumption: A “True” Twitter-er has at least 10 followers, follows at least 10 people and had tweeted at least 10 times. By that definition though, only 21 percent of Twitter users are active users.

What’s more, last August the website hit 23.5 million users and recorded a traffic high in July which it has failed to get near since. But not only this, the users it does have have become increasingly inactive.

This begs the question, has Twitter hit its peak?