So what is platform?
My understanding is that platform is a buildup of readership and/or a following of people who like to read what you write enough to buy it. Of course, the bigger your platform, the easier it is to sell your books and to get your books published through a publisher. Platform is becoming a more important reason why good authors are being rejected. The writing may be good, the concept interesting and applicable to the time, but if the author doesn't have a great platform, it can be rejected based on that alone.
So the great question for every author is: How do I build a platform? It all boils down to marketing and promoting. Those who are great at marketing themselves, speaking in public, and building that public awareness will build a bigger platform and have the edge over the writers who don't market and promote themselves well.
I'd like to point you to some great articles that have been written on this topic lately:
I'll be covering more on this topic in the future, since it is so vital to our survival as authors in this world of publishing.