Twitter is a microblogging site, restricting posts, i.e. Tweets, to 140 characters or fewer. This limit allows real-time posts to be made using SMS (short message service) technology, which is the basis for text messaging on cell phones and other mobile devices. Tweets can also be posted online at twitter.com. As of January 2010, over . . . → Read More: What is Twitter and Why Scientists Need To Use It.