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 9.4% to reach $134 billion by 2021. The US is the largest market, accounting for nearly 40% of the global paid search market in 2015. This forecast details global paid search market size and includes data for 13 countries plus a breakout by mobile and desktop.