The explosion of freelance work in recent years has been called many things. Some refer to "liquid workforces," others to "agile talent," and others talk about "the gig economy." But whatever terms are used, it is clear that many employers and their HR staffs will increasingly be dealing with freelancers, and the unique working world that they inhabit.

According to the Deloitte Human Capital Trends report, more than 30 percent of the U.S. workforce now consists of freelance or contract workers, and more than half of employers expect the demand for freelancers will continue to grow.

In a recent article for the Huffington Post, Ellyn Shook, Chief Leadership and Human Resources Officer at Accenture, said the digital revolution is forcing companies to become much more flexible with their workforces. "Leading companies must blur traditional boundaries to broaden their definition of 'workforce' — finding the right combination of internal employees, freelancers and technology for each new challenge," she wrote.