Publishers today only want to publish books by authors with a “platform.”
A platform is (1) a visible presence in a market and (2) one or more channels through which you can reach that market.
Editors looked for such things as whether the author had a column, TV or radio show, even an infommercial.
But now, as a potential author you have to build your platform online too.
In your book proposals, publishers want to know: (a) number of Facebook fans, (b) Twitter followers, (c) LinkedIn connections, (d) sales of prior books, which the can now confirm easily online, and (e) web site statstics especially unique visits per month.
If you ignore social media like I do, you are soon going to find it next to impossible to sell your book idea to a mainstream publisher.
With everyone self-publishing POD (print on demand) books and Kindle e-books today, maybe that doesn’t much matter to you.
But I’m old school. I like “real” books — books that are made of paper, professionally designed, and published by a traditional publishing house, which still (in my opinion) produce books of quality a full step higher than the average self-published affair.