Certain sectors of the economy remain extremely robust despite global macroeconomic challenges. In particular, the mobile app economy is expected to reach surpass $25 billion this year, according to ABI Research. Smartphones are expected to rake in $16.4 billion of app spending, leaving $8.8 billion for tablet app spending. By 2018, ABI expects that tablet app purchases will grow larger than smartphone app spending. In this video, Motley Fool contributor Steve Heller discusses the details of this report and which companies are likely in the best position to benefit. The two big winners? Apple (NASDAQ:AAPL) and Google (NASDAQ:GOOGL)