Paid search is currently the largest interactive marketing category, but it will face tough competition from social advertising in the coming years. We forecast that the global paid search market will grow at a five-year compound annual growth rate (CAGR) of 9.8% to reach $136 billion by 2021. The US is the largest market, accounting for nearly 40% of the global paid search market in 2016. This forecast details the size of the global paid search market and includes data for 13 countries plus a breakout by mobile and desktop.