Picture it: the author sitting alone in a garret writing. Brief dealings with editor and publisher are the only contact the author has with the outside world. The goal is to write and that's all the author does.
That description no longer exists for authors in today's publishing world. Not only must the author write the book, she must promote it. While this trend has been going on for decades (probably longer in some cases), social media has caused it to explode.
It's more than the occasional book tour and the odd newspaper review. Most authors today not only have their own websites, they have Facebook pages and blogs. You can follow them on Twitter and Pinterest. What about those authors who use different pen names? They often have all of these accounts for each of their names!
Some people may think that such promotion is only necessary for authors that self publish or perhaps work with small publishing companies. Not true. Authors published by the Big Boys of the publishing world promote themselves just as much. It doesn't matter if the book is the author's first or she's already a New York Times Bestseller.
With all the blogging, tweeting, and posting all over I don't know how authors find the time to actually write the books. I'm just grateful that they do!