Golf club manufacturers have long placed ads in printed golf magazines. Movie studios tend to run television spots before a weekend rather than after.

Targeting has become even more precise as advertising moved to the Internet.

At first ads were largely targeted to Web sites or sections geared to specific topics. An ad for food products might appear on a cooking site.

Then came search and the ability to target messages even more precisely based on what you’re looking for.

But increasingly, online time is spent connecting with friends at News Corp.’s MySpace or Facebook — places that aren’t focused on a single topic and may not have good keywords in the text. Even when good keywords like “Hawaii” or “Porsche” are available, Web sites can’t always meet advertisers’ demand for popular topics like travel and autos.

Enter behavioral targeting.

If you’ve been browsing a lot of Web sites on Chrysler LLC’s Dodge Grand Caravan, a “cookie” data file on your Web browser might mark you as being in the market for one. Next time you’re on a Web site about cooking, don’t be surprised if Caravan ads follow you there.

Although the concept has been around for years, enough Web sites are now participating in ad networks that advertisers can still reach a sizable group even if they target narrowly.

That’s especially true for “retargeting,” a form of behavioral targeting in which offers and promotions for a company appear across the Web if you’ve previously visited that company’s site but didn’t buy anything. Think of it as a retail store employee chasing you down the street and around town with a coupon.

In the past, finding you again to deliver that promotion might have been difficult, because Web sites weren’t a part of larger networks. Web sites are also targeting more smartly.

Companies, for instance, are pouring through data on Web surfing to perhaps find that high-definition television owners also like to travel or buy expensive jewelry. Or they might find a correlation between reading obituaries and renting cars — seemingly disparate, until you remember you need to get to the funeral somehow.

All that takes better technologies and better interpretation of data by humans, the chief executive of Specific Media Inc., an ad-targeting company, Tim Vanderhook, said.

“That’s something that over time will get better,” he said. “We’re in about the second inning of a nine-inning game.”