Twitter is growing at an impressive pace in one key area, but monthly usage is actually down

Twitter is not the world's most popular social networking service, but one number considered essential for the prosperity of the San Francisco-based company continues to grow at a healthy pace, which should keep investors relatively happy for the foreseeable future.

Interestingly, the metric Twitter is focusing on as the "best way to measure" its success counts so-called monetizable daily active users rather than the MAU (monthly active usage) number generally employed by rivals to flaunt their progress. These monetizable daily active users (mDAUs), which are defined as Twitter ...