My first novel, High Fidelity, was published in 1995, and shortly afterwards, I embarked upon my first American book tour. I took with me a Discman, and 15 or 20 carefully chosen CDs in a wallet, although I bought lots of others while I was there – CDs by bands I'd never heard of, and wouldn't have been able to buy at home, recommended to me by people who came to readings, or by journalists at the end of interviews. There was always a thriving, intimidating independent music store just a short walk from my hotel, in whichever city I was visiting. At signings, people gave me lovingly made compilation tapes, occasionally demo tapes of their bands, or their friends' bands, and sometimes bootleg tapes of shows by artists they thought I'd like. Towards the end of the tour I no longer had room for it all, and I had to leave little piles of cassette boxes next to the waste-bins in my hotel rooms. (I couldn't bear to put them in the bins. I wasn't throwing them away; I was leaving them behind. There was a difference.) If you look at the above picture carefully, and compare it to your average 2009 book tour, you should be able to spot the differences. Even spoken-word recommendations look quaint now.

Back then, the future of music didn't look particularly interesting to me. I don't mean that music itself seemed boring, although I was 38 years old, and I felt like I'd heard a lot of the mid-90s before. I mean that neither I nor anybody else I knew spent any time thinking about how our consumption of music might change. How could it? There wasn't much to it, surely? OK, someone might come up with another format, something that might sweep away the compact disc just as the CD had replaced vinyl. But whatever it was, all you could do was buy it – which meant walking down to Our Price, or a local independent store staffed by people who looked as though they'd rather have their heads stuck inside Thurston Moore's amp than speak to you. I certainly couldn't have imagined writing a novel which is in part about how we relate to music in the 21st century. Like most of us, I believed that this relationship would be a version of the relationship we all knew and loved, with a couple of extra volume knobs on.

In the year that High Fidelity was published, a new CD shop opened in my neighbourhood and rejuvenated my listening habits. The shop did well, initially, and I spent a lot of time in there, buying pretty much whatever the owners told me to buy; they were very clever, it seemed to me, in targeting the ageing (or perhaps, more precisely, ex-) hipsters of north London, people who were growing sick of their REM albums but didn't know what else to buy. They sold hundreds of copies of Buena Vista Social Club, and a lot of tasteful trip-hop – which, as Simon Reynolds pointed out, was "merely a form of gentrification". But then, what are you supposed to do if you're becoming gentrified? Pretend it isn't happening? Yes, Portishead sold a lot of albums to people who wanted to listen to music that meant something without waking up their children, but that's not necessarily a desire that deserves a sneer. Keeping in touch with the things that help us feel alive – music, books, movies, even the theatre, if, mysteriously, you are that way inclined – becomes a battle, and one that many of us lose, as we get older; I don't think enough of our cultural pundits, people who write about that stuff for a living, fully understand this. It's one thing to have an opinion on Little Boots remixes if you earn your living hanging about in cyberspace; quite another if you're a full-time teacher with three kids. My friend's CD shop performed a valuable service to those whose shopping and browsing and listening time was rationed by circumstance, people who had the occasional five minutes on a Saturday morning to check out, and sometimes even buy, what everyone else was listening to.

You'll know what happened to the shop, because it happened to everyone else's shop, too. Illegal downloading wouldn't have been a factor here – the punters were too old and, for the most part, too well-heeled for all that. But Amazon started selling CDs for less than my friends could buy them for, and eventually even north London's late adopters worked out that one-clicking didn't take much effort. The trouble with this, of course, is that you're shopping in a vacuum, however many times you're told by some robot you don't know that if you like this then you'll love that. You're feeding off nothing, apart from recommendations in broadsheet newspapers and magazines such as this one – and we've all been burned like that. After my local CD shop closed down, I was getting ready for a musical life that turned in on itself, before dying slowly from malnutrition. Any piece of music becomes drained of meaning and excitement if you listen too much to it, but a three-minute pop song isn't going to last you a lifetime. Popular music needs to keep flowing. If the fresh supplies stop, it's you that becomes stagnant.

It took me longer than it should have done to work out that the internet is one giant independent record shop – thousands and thousands of cute little independent record shops, anyway – and they don't actually charge you for the music they stock. The MP3 blogs that stretch for miles and miles, as far as the eye can see, down that stretch of the net that isn't reserved for pornography, are staffed by enthusiastic and likable young men and women who absolutely don't want to rip the artists off: they are always careful to post links to iTunes and Amazon, and the songs they put on their sites are for sampling purposes only. (For the most part, they are encouraged to do so by the artists and their labels, who take out adverts on the more popular sites, and are clearly sending advance copies of albums to the bloggers.) It works for me. I listen, and then I buy what I like, because owning music is still important to me. If the music I like stays out there in cyberspace, as it does on Spotify, then somehow it cannot indicate character and taste in the same way, although I doubt that younger generations will feel like this, and good luck to them.

But it's easy. Look at Hype Machine (hypem.com) to begin with: in the top right-hand corner of the site, you'll see a list of the top five most-blogged artists, so you will get a sense of what's going on out there (or in there, if you are a literal-minded soul). The search engine will offer you a chance to listen to these artists, and, in the process, you'll get the chance to discover your favourite virtual record store, because every single one of those links you see will take you to a different MP3 blog. My favourites are I Am Fuel, You Are Friends, Largehearted Boy, Aquarium Drunkard, When You Awake, and Funky16Corners. (Some of those names are indicative of a generosity of spirit that one doesn't always associate with the internet.) And some of these post songs from new bands, and some post scratched old vinyl funk records, and if you spend an hour messing about you'll find 20 or 30 great songs you never knew before. In other words: there's no excuse.

Juliet, Naked is in part about how a middle-aged man devotes a large chunk of his life to keeping alive the work of a long-forgotten 80s singer-songwriter; he runs a messageboard, posts essays online, and virtually lives in a virtual world, talking to people he wouldn't ever have met 10 years ago. Perhaps one of the paradoxes of music on the internet is that it's perfect for the old folks. If you need to find set lists for every show Rory Gallagher ever played, I'm sure there's some chap with nothing better to do who is taking care of it right now. But more importantly, you need never again feel as though the pop life is drifting away from you – indeed, the anonymity and user-friendliness of the MP3 blogs mean that one feels emboldened to walk into even the scariest-looking website in the full confidence that nobody will laugh at you.

I'll be off on a US book tour again soon, to promote a novel that is, in part, about how the world has changed since 1995. I'll be taking with me a small black box, no bigger than a packet of cigarettes, containing every piece of music I've ever loved. And a lot of that music – more than I could possibly have imagined five years ago, when I was prepared, reluctantly, to pull up the drawbridge – was made very recently. And no, I don't know how it will all pan out, who will pay the artists to make their lovely or ugly or scary music in a world that's increasingly beginning to expect everything for free. (My best guess is that being in a band will become a version of national service or the Peace Corps; something you do for a couple of years before knuckling down to a proper job. And the London Symphony Orchestra won't appear on as many rock albums as they used to.) All I know is that if you love music, and you have a curious mind, there has never been a better time to be alive.

• Juliet, Naked (Viking) is out now.