Worldwide public cloud services revenue reached $45.7 billion in 2013 and will grow at a compound annual growth rate of 23 percent through 2018, according to the newly released “Worldwide Semiannual Public Cloud Services Tracker” from International Data Corp.

Two product groups comprise the total public cloud services market in IDC's research: cloud software and cloud infrastructure. Cloud software spending represented almost 86 percent of the total public cloud services market in 2013 while cloud infrastructure accounted for the remaining 14 percent.

The cloud software market includes software-as-a-service and platform-as-a-service. The SaaS category has been mainly driven by enterprise applications such as enterprise resource management and customer relationship management, as well as collaborative applications. The PaaS market has been largely driven by integration and process automation and structured data management offerings, and application server middleware.

The cloud infrastructure product group includes only infrastructure-as-a-service, which is comprised of server and basic storage.

On a regional basis, the United States holds almost 68 percent of the public cloud services market, which IDC says is much more than what it holds for traditional technologies. Western Europe holds 19 percent and the rest of the regions hold 5 percent or less each. By 2018, IDC forecasts that the U.S. share will drop to 59 percent while Western Europe will grow to 23 percent of market share. Emerging regions are also expected to grow above worldwide average.

"Data provides the edge to companies that can leverage their information for competitive advantage, through new products and services or an enriched customer experience,” Frank Gens, senior vice president and chief analyst at IDC, said in a statement. “Software for data management, data access and collaborative information sharing continues to lead the growth in the overall software industry."