‘You can have any colour as long as it’s black,’ said Henry Ford following his invention of the mass production factory line. These days he would say, ‘You can have whatever colour you want plus an infinite combination of fixtures and fittings.'

The massive change brought about by the digital age has affected all businesses, as I was reminded listening to Peter Day’s The World Turned Upside Down on BBC Radio 4. I discovered very quickly for myself that retailing wasn’t what it used to be when I opened my shop in Winchester six years ago. Before I was a marketer, I was a bookseller. In those far off days, booksellers bought mass produced books to sell in a local bookshop. I gave customers a choice of titles as far as space would allow.

I imagined the situation would be similar when my wife and I opened our gift shop. Instead, I found that my customers’ choice now extended to the hundreds of retailers on the internet. Which meant a much greater choice of products as well as prices. We soon concentrated on handmade goods which are always unique in some way.

It would have been worse if I’d gone back into the book trade where Amazon was offering readers pretty much every book published. Today, with the advent of e-books, anyone can publish their own book or set up as a publisher and sell books of the most minority interest, even extreme sexual fantasies, according to an outraged Mail On Sunday.

This is the unstoppable trend. As a dinosaur who grew up in the pre-digital age of mass consumption, I, like most of us, am only beginning to understand the new customised world we find ourselves in. Modern technology allows a retailer to find out exactly what each customer wants and, by way of 3D printing among other things, makes it possible to provide it. Peter Day quotes Joe Pine of Strategic Horizons, 'Customers don't want choice, they just want exactly what they want.'

Take your mobile phone as an example. (How quaint that we still call this handheld data processing device a ‘phone’.) You can choose from thousands of apps and end up with a unique mixture that reflects exactly what you need.

Google has become the world's biggest media business by providing millions of advertisements targeted to individuals who themselves are provided with customised search results.

Your choice of music is no longer dictated by what record shops stock or a handful of music stations play. Now you can download any track you like, even the most obscure self recorded singer, or tailor your streamed listening to match what you already know you like. You prefer Ambient House to Acid House or Glam Metal to Gothic Metal? No problem.

Internet entreprenur Joe Kraus expresses it succinctly: 'The 20th Century was about dozens of markets of millions of consumers. The 21st Century is about millions of markets of dozens of consumers.' I think one of the reasons why theatre and other live performances are increasingly popular is that the experience is customised to each night's audience and each person in that audience can have an effect on it.

Yes, there are still big hits that gain a mass audience but these are increasingly sourced from and driven by today’s customised media. So Justin Bieber began his career by posting a video on YouTube and 50 Shades Of Grey started as fiction self-published on a website.

As Will Self pointed out in The Observer, instead of relying on an elite handful of critics, curators, publishers or producers to tell us what to like, we are turning to the many individuals who post and vote on the web and together create a critical mass known as 'trending' or 'viral'.

You can still sell a mass produced product and try to compete on price but it’s a race to bankruptcy. The successful businesses of the 21st century will be the ones who find ways to provide you with exactly what you need exactly when you need it.

This blog was written by Paul Lewis, owner of the marketing consultancy The Lewis Experience and online retailer Your Life Your Style, and former Head of Marketing and Operations at The Mayflower Theatre. You can connect with him on Google+ and LinkedIn.