The online musical universe has become Balkanized, with many sites focusing on minute niches. That works well for reaching very specific demographics, which is wonderful for advertising, but it flies in the face of the common wisdom that people's tastes have become more diverse as music of any description has become a mouse-click away.

Bon Jovi's trick is to use heavy-metal chords and still sound absolutely safe. Rock & roll used to be rebellion disguised as commercialism; now so much of it is commercialism disguised as rebellion.

The most surprising and rewarding chapter to write was the Butthole Surfers chapter. I'd always thought of them as a bunch of drug-addled reprobates - which maybe they were - but it turned out to be more complicated than that.

I would roll out of bed and immediately start working, and keep working until it was so late at night that I couldn't stay awake anymore. Then I'd go to sleep and wake up the next morning and do the same thing all over again. I did that every day for three years.

Critics and fans use the music of their youth as reference points. For years, people seriously wondered who "the next Beatles" were going to be, and classic rock bands were the de facto yardstick for rock quality.

Naturally, no one knows more about music than musicians. They talk about their own work all the time, but they rarely get to talk about other people's music.

Now that the generation that grew up on '80s indie-rock has attained influential positions in the culture, that music is the new yardstick. And that will shift yet again some day.