Back in the dark ages — say, 1995, — there was an upstart little website called Amazon.com that fancied itself as the first real online bookstore.

People didn’t need to try a book on or squeeze it for freshness, the logic went, so books were a natural for e-commerce.

Flash forward to 2011, and Amazon says everything has changed. With its Kindle e-reader, it now sells more eBooks — electronic downloads of books — than it does physical books on paper. And if leaked stories are to be believed, Amazon is looking into becoming “a Netflix for books,” offering as many books as you care to download for a fixed annual subscription price. (Amazon has not commented on the story.)

Oh, how things change. It’s been some years since the book began to be transformed from a physical object to a digital file; now we’ve reached a tipping point. People are readily buying eBooks, in rapidly growing numbers, while conventional book chains like Borders go out of business.

“We can easily say that eBook sales in the U.S. will grow from just less than $1 billion in 2010 to more than $2.8 billion in 2015,” said James McQuivey of Forrester Research, Inc.

There are still plenty of conventional books out there, of course. Paper is convenient, portable, nice to look at, and doesn’t have batteries that run out. At the end of last year, McQuivey said, just 7 percent of American adults with online access read eBooks.

But that number will double by the end of this year, he predicted, and e-readers, led by the Kindle, are making a big difference.

“Once people catch the eBook reading bug, they rapidly shift a large portion of the books they read to digital,” McQuivey said.

All this is obviously fearsome news to bookstores, just as Napster and the iPod brought record stores to their knees. And it will mean seismic changes for publishers, who stand to make less money from book sales, but spend less on printing and shipping.

But what does it mean to you? Well, how much time do you have for reading?