Advertising spending continues rebound.

• Position: YOUR LIFE

Global expenditures on advertising grew 3.3% in 2012 to $497,300,000,000, a gradual rebound since the sudden 9.6% drop in 2009 as a result of the economic downturn. Spending has responded to shifts in popular media with Internet advertising the fastest-growing sector in 2012, now accounting for 18% of the total, according to a "Vital Signs" report by Worldwatch Institute, Washington, D.C.

U.S. advertising expenditures grew by 4.3% in 2012 and remain nearly one-third of the global total. The Asia Pacific region accounted for the fastest growth, however, with ad spending there increasing by 7.9% (excluding Japan, which grew by 3.1%). Expenditures fell by 2.2% in Western Europe, the only region to sea a decline, largely due to the ongoing Eurozone crisis.

The growth in spending on Internet ads has been driven by the expansion of social media and online video advertising. Mobile and social media now account for over half of all advertising revenue in the U.S., for example, having increased by more than 30% in both 2011 and 2012.

"As consumers grow overexposed to advertising, traditional forms such as television commercials, print advertising, and billboards are becoming less effective," says study author Shakuntala Makhijan. "As a result, advertisers are turning to more subtle techniques, such as promotional material on blogs, product placement, and interactive advertising on social media such as Facebook and Twitter. The distinction between advertising and media content is therefore increasingly blurred."

Advertisers also have focused more resources on "green" ads aimed at attracting consumers with unsubstantiated claims of...