This is the second quarter the company reported earnings since Google founder Larry Page took the helm as CEO. In the first quarter, Google reported profits of $2.3 billion on $8.58 billion in revenue, up 27% compared with the year-ago first quarter.
The sites owned by Google generated $6.23 billion, or 69% of total revenue, in the first quarter of 2011 -- representing a 39% increase compared with first-quarter 2010 revenue of $4.5 billion.
Partner sites generated revenue through AdSense programs of $2.48 billion, or 28% of total revenue, in the first quarter of 2011. This represents a 20% increase from second-quarter 2010 network revenue of $2.06 billion.
Aggregate paid clicks from search campaigns, which include clicks related to ads served on Google sites and the sites of its AdSense partners, rose 18% compared with the year-ago quarter and down 2% from the first quarter of 2011.
The average cost-per-click, which includes clicks related to ads served on Google sites and the sites of its AdSense partners, increased 12% over the first quarter of 2010 and rose 6% over the first quarter of 2011.
Google said traffic acquisition costs -- the portion of revenue shared with Google's partners -- rose to $2.11 billion in the second quarter of 2011, compared with TAC of $1.73 billion in the second quarter of 2010. TAC as a percentage of advertising revenue was 24% in the second quarter of 2011, compared to 26% in the second quarter of 2010.