A freelance worker, or self-employed worker, is the person who are not necessarily committed to a particular employer long-term.
Sometimes, workers are represented by a company or a temporary agency that resells freelance labor to clients; others work independently or use professional associations or websites to get work.

Keep in mind that freelancers are workers who handle all activities by themselves, including contracts, legal issues, accounting, marketing, and other business functions. They might choose to pay for professional services or hire another worker to handle some of the workload, but for most cases, these are very short-term contracts.