What’s interesting about this Twitter blog post claiming 100 million active users is that they qualify the user count with the word “active”. Of course we know that active users are all that matter, but it is not a common way to bill your service — especially when it is estimated that you have over twice as many “users”.
Twitter does a piss poor job of clarifying what active means, while over on Paid Content Ingrid Lunden states:
The 100 million active monthly users, which are based on people sending a Tweet in the last month, is an increase of 82 percent since January 2011.
I don’t buy that Twitter would do that poor of a job measuring active users. Since you can be a very “active” Twitter user and never post a tweet.