Nope. Definitely not. Lots of folks have multiple, multiple Twitter accounts and millions of others have opened Twitter accounts that are sitting around virtually untouched.

So how many people actually use Twitter every day or every month? An exact number is a mystery. Twitter doesn't give out active user information, just the total number of accounts ever created on the service.

So it's up to third parties like comScore -- and others -- to track Twitter traffic. Click here to see an Excel chart by comScore on Twitter's traffic.

comScore counts unique monthly visitors to Twitter's website. For the chart -- its clear the explosive growth at Twitter is over. Still the folks at comScore say their figures probably undercount Twitter's total traffic by 10 to 15 percent. comScore misses people who only use third party apps or mobile devise to log onto the site.

Check out my story on how Twitter is getting serious about making revenue. And follow Marketplace on Twitter.