The big online buzz in recent years has been over paid search as it rose up out of nowhere to become huge, overtaking display advertising. It was the hot thing.

Here's the next hot thing: online promotions--such things as games, contests, coupons and public relations.

A new forecast has online promotions nearly tripling over the next five years, to $22.8 billion in spending, to become the dominant form of online advertising. Display advertising will begin declining after this year, in terms of spending, and search will do so after next year.

“It is dramatic, but it is something that has been happening over all media for decades,” says Gordon Borrell, CEO of Borrell Associates, which issued the forecast.

Borrell says promotions now make up 60 percent of marketing spending by companies, and he expects that share to grow further in the coming five years, with online promotions playing catchup.

Currently, online promotions account for only 22 percent of online marketing expenditures.

One reason online promotions are expected to see such growth is that they are highly measurable, and marketers often see a direct effect in the form of improved sales.

Another reason is that certain types of promotions, such as contests and games, allow the advertiser to establish a direct link with the consumer.

With an ad, the advertiser gets an impression and maybe a click-through but no real sense beyond the numbers of what's in the mind of that consumer seeing the ad. “The internet is a targeted interactive media, and banners are counter-intuitive to that. They are the old mass media idea,” says Borrell.

Contests engage the consumer, in some form or another getting him or her to give up information. According to Borrell, that addresses one of the few shortcomings of the internet, that it does not evoke strong emotions and identification with a product as well as some other media.

Borrell is forecasting that online display advertising will peak at $12.6 billion this year and then decline sharply to just over $5 billion in 2012.

Paid search advertising will peak next year at $16.9 billion, predicts Borrell. “Search will flatten and then decline in favor of new forms of spending, like promotions -- something a lot more interactive.”

Among various forms of promotions, games and contests will be the big gainer, growing from 10.5 percent of online promotional spending last year to 28.4 percent in 2012.

But the biggest area will remain online discounts and rebates. Last year, they made up 41.4 percent of spending. By 2012 that share will dip to 38.7 percent.