Facebook, Twitter, Google+, and smartphones are today's social media; but in the 17th and 18th Centuries the written word in the form of letters and short notes, were social media. In the 17th Century public postal systems had come of age. Now it was possible for the ordinary citizen to communicate with others just as heads of state had been doing for years. This rise of the postal systems caused an explosion of letter writing. Voltaire wrote as many as 10 to 15 letters a day and dramatist Jean Racine complained of not being able to keep of with all of the letters. The equivalent of a full inbox. What was the subject of all of these letters? Not much, invitations to dinner, and OMG, did you hear about the king? One woman over the course of 26 years sent her daughter over 1,000 letters on the coming and goings in Paris.
Another form of writing much like Twitter today was les billets, little bits of paper with inflammatory words about politics that were thrown about in public. These little slips of paper were a way to organize uprisings and bypass government censors.
To learn more about these writings and the Mapping the Republic of Letters project see:http://news.stanford.edu/news/2011/november/old-social-media-110211.html