Since the invention of movable type until very recently, if an author wrote a book and wanted it published there were only two routes; either finance the printing and distribution of the book themselves or persuade someone else to invest their money in it in the hope of getting a decent return.
The first requires money - and that's just for the actual printing not to mention distribution. As not every would-be author is blessed with enough cash monies to cover this kind of outlay this necessarily means that the second option must be relied on. But again here is a problem because publishers can only publish so many books a year, which means that they must necessarily be selective. That selection is going to be based on the tastes and judgement of (usually) one person. Your book may be amazing but if that one person doesn't 'get' it, nobody will get to read it (the same thing happens in the music industry, which is why nearly all music on the radio is stuff Simon Cowell likes). There is also the problem of volume of submissions - not all manuscripts can be read.
Up until a very few years ago this had been the situation for generations. Either pay for a limited print run of your book or rely on someone else to actually give it a chance and like it and put it into general circulation.
Then came the eReader. The cost of producing a printed book from written copy is large. The cost of producting an eBook from written copy is essentually zero. So now the field is open for independent authors to get their work out there and be read. Maybe not by a mass audience but by an audience all the same.
Once the book is released it is then a question of promotion. This is going to be easiest by social media - Twitter, Facebook, whatever works - and get people to review the book wherever it is available, on reading sites such as Goodreads etc. Word of mouth can be powerful and a good word on social media and peer reviews are more highly regarded than professional criticism when it comes to something as personal and time consuming as reading a book.
And distribution is electronic, direct to the eReader or via eBook distribution sites (either independent like Libiro (www.libiro.com) or commercial like Amazon) so there are no significant costs there either.
Which brings us to pricing. One of the great things about independent writers is that they don't have a whole paper book publishing and distribution arm and a lot of employees to finance. So the books can be inexpensive - a pound or two each - which also encourages sales. A great marketing tactic is also (if an author has more than one book to sell) to give one book away free to encourage a readership.
My eReading is almost exclusively 'indie' authors. I like reading these works that almost inevitably would never have been available previously. They may not always have the polish of a professionally (read: expensively) edited book but as with all works it is the core idea that is the point. Sometimes these are just slightly outside of expectation - and that is the real delight, finding a book that would not have been accepted for a large print run by a publisher but are nevertheless little gems of ideas well expressed.
Of course traditional publishing still has a large (major in fact) role in keeping the nation reading. But here's a shout out to those independent authors. Go and grab an eBook and enjoy something a little bit different today.