U.S. online advertising revenue has hit an all-time high, the Interactive Advertising Bureau reported yesterday.

According to the IAB, which enlisted PricewaterhouseCoopers to help prepare the results, online ad spending hit $26 billion last year in the U.S., representing a 15 percent gain year over year.

In the fourth quarter alone, advertisers spent $7.45 billion on the Web, jumping 19 percent compared with the fourth quarter of 2009.

Search advertising continued to be the most popular choice among advertisers, totaling $12 billion last year. Advertisers spent $9.9 billion on "display-related" ads, including banners, sponsorships, and digital video commercials. Classifieds and directory ad spending hit $2.6 billion.

In a separate report released yesterday, Econsultancy delved into search marketing. The company found that advertisers spent $16.6 billion in the U.S. and Canada on search marketing last year, translating to a 14 percent gain over 2009. It expects search marketing revenue to hit over $19 billion this year.

IAB estimated that U.S. mobile ad revenue last year was between $550 million and $650 million. It was the first time IAB included mobile ad revenue in its annual report on the status of online advertising.