Keyword search ads led the sector, representing 41 percent market share and $5.1 billion in revenue, followed by total display advertising, with 34 percent market share and $4.3 billion in revenue, and classified advertising with 17 percent market share and $2.1 billion in revenue.
Display advertising includes subgroups of display, sponsorship, slotting fees and rich media.
Nearly half (46 percent) of the ad deals were cost-per-thousand impressions, which include display and banner ads, followed by performance deals, which include cost-per-click and cost-per-transaction, which accounted for 41 percent of the online-advertising contracts.
In the fourth quarter of 2005, Internet advertising revenue totaled $3.6 billion, up 34 percent from the year-earlier period.
