Twitter is the most widely used social networking site after facebook. I am also using twitter for many years now. Every new user that comes to internet first move to facebook and then twitter. You can follow people on twitter and likewise other people also follow you back.
Twitter recently announced that 218 million users (per month) are using twitter all around the world. This is very large amount of traffic twitter is getting. Most of the revenue of twitter comes from its mobile users including tablets users. About 162 million users (per month) use twitter from mobile and twitter announced that it is getting most of its revenue from mobile users.
The amount of visitors on twitter is less than facebook i.e. facebook is getting 845 million users per month. Every user on internet use facebook once or more time in a day. Some users like me is always online on facebook when turn on my computer. But the important thing is that twitter users mostly use twitter by third party apps and update their tweets through them. There are very few users who visit twitter official site to update tweets. And twitter is getting lot of interest from mobile apps users.