Professional certificates are bundles of related courses that help you master a specific skill, and they tend to be most useful for breaking into a new industry or getting you to the next level of your career. They can take anywhere from a few months to more than a year to complete. At Coursera, professional certificate programs typically have a 7-day free trial and a monthly fee afterward. So, the faster you complete it, the more money you'll save. At edX, professional certificates typically have a flat one-time fee.