Social media “users,” as we are all well aware, can have quite the variance to the amount of “use” they give to the social network in question. Not only that, but the word “user” doesn’t even necessitate any human element.

So, with thoughts of bots and inactive human users rattling around your brain, it looks like Twitter has finally crossed the 500 million user mark.

That’s the news according to analyst group Semiocast, who says that Twitter crossed the half a billion user threshold back in June. They also say that 140 million of those users are from the United States.

By comparison, Facebook just reported in their Q2 earnings that they now have 955 million “active” users. That’s a monthly figure, as the daily active users tally is around 552 million.

Back in September of 2011, Twitter CEO Dick Costolo said that there were 100 million active Twitter users. And in March of this year, as Twitter celebrated their 6th birthday, they announced that there were 140 million active users. If we do a little math and assume that the growth rate stayed roughly the same, we can assume that there would be about 160 million active Twitter users by now.

So, the discrepancy between this figure and the 500 million figure is all about “users” vs. “accounts.” If Semiocast found over 500 million accounts and Twitter’s growth rate in active users hasn’t skyrocketed since March of 2012, that means that there are a whole hell of a lot of worthless and bot Twitter accounts out there. A pretty hefty majority, actually.

Other fun facts from the Semiocast study:

• Japan, while growth is slowing, still remains the second most Twitter-happy countries.  They post 10.6% of all public tweets, worldwide.
• People only tag tweets with a location 0.77% of the time
• Arabic usage is growing on Twitter, as it’s now the 6th most popular language on the site.  I’m sure this has something to do with Twitter launching in right-to-left languages (including Arabic) back in March.