The first blog software to get really popular was Movable Type (http://en.wikipedia.org/wiki/Movable_Type). MT was basically a set of Perl scripts that provided a nice GUI backend to manage content stored in a database. But the actual public-facing sites it created were all static files. When you hit "Publish," it would scan over the database and grind out a new set of static HTML files.

This made scaling a Movable Type site really easy, because even back then Apache could serve static files like a monster on practically any hardware. But it meant that when you changed something on your site, that change didn't show up there immediately; you had to wait for a rebuild operation to complete and a new set of static files to be ground out to see it. The larger your site got, the longer that rebuild operation could take. "Rebuilding" became to Movable Type what "buffering" used to be to RealPlayer (remember that?).

Then, after a few years of MT being the leading product in the then-rapidly growing blog market, the developers behind it decided to jack up the pricing structure for it (http://scott.yang.id.au/2004/05/license-changes-with-movable...). MT was not open source, it was proprietary, for-pay software, so if you wanted to use it you had to pay what they asked for it. And suddenly it looked like, instead of being twenty bucks, a valid MT license was going to cost hundreds.

As you can imagine, people freaked out and started looking at the available alternatives. There were lots, but none of them were particularly impressive at that stage. But some prominent people (see http://web.archive.org/web/20060410125402/http://diveintomar...) noticed a little project called WordPress that, while pretty feature-poor compared to MT, had two big things going for it: it was 100% GPL (so no worries about future price changes), and it used a dynamic publishing model where pages were generated live on request through database queries instead of being baked into static files.

"Hooray!" everyone yelled. "No more rebuilding!" And so the rush to WordPress began. It was pretty obvious at the time that using live, dynamic pages would be a scaling headache. But most blogs never get enough traffic for scaling to become an issue, and dynamic pages meant not having to wait for rebuilding anymore. Never underestimate the power of appealing to impatience.

The irony, of course, is that once WordPress got popular, people started noticing how inefficient dynamic pages could be, and the trend of the "static site generator" was born. SSGs are now very hot and buzzed-around, at least among programmers (they're generally too nerd-optimized to appeal to the general market). But there's nothing really new about the idea; they're just the pendulum swinging back to where Movable Type was in 2001.

Perhaps someday an SSG will dethrone WordPress. If that happens, mark your calendar; you'll want to be prepared when "instant updates!" become a selling point again, five years or so later.