The worldwide online advertising is forecast to hit US$65.2 billion in 2008, and rise to $106.6 billion in 2011, according to the IDC Digital Marketplace Model and Forecast Media Post reported.

“(Though) Internet advertising is growing at a phenomenal rate, (it) is still relatively new and growing from a much smaller base. By the end of the forecast period, spending for Internet advertising will trail direct mail by more than $30 billion, while spending on TV and print ads will each be nearly twice as great as for online ads,” said John Gantz, chief research officer at IDC.

“The long-term opportunity for Internet advertising can be seen in the disparity in per capita spending: total advertising revenues are more than $105 per inhabitant of the planet, while Internet advertising revenues are less than $50 per active Internet user,” he said, according to Media Post.

Other key findings and predictions from the IDC report include:

• Keyword ads will still dominate online advertising throughout 2011, generating more than one-third of annual online ad spending worldwide
• Display ads will be the second largest, capturing more than 20 percent of global online ad spending annually through 2011
• Classifieds will bring in nearly 19 percent of all online ad spending per year
• Rich media ads are expected to increase at a CAGR of more than 50 percent from 2007 to 2011

"Marketers already recognise that online advertising must be incorporated into any comprehensive ad strategy. This will continue to drive growth in online ad spending well beyond the forecast period," said to Karsten Weide, programme director of Digital Media and Entertainment.

"However, there is still a lot of experimentation underway within the category as marketers seek the optimal mix of ad types to reach their target audience. This will fuel spending for all types of online ads," Weide added, according to Media Post.