A limited liability company is the United States-specific form of a private limited company. It is a business structure that can combine the pass-through taxation of a partnership or sole proprietorship with the limited liability of a corporation. An LLC is not a corporation under state law; it is a legal form of a company that provides limited liability to its owners in many jurisdictions. LLCs are well known for the flexibility that they provide to business owners; depending on the situation, an LLC may elect to use corporate tax rules instead of being treated as a partnership, and, under certain circumstances, LLCs may be organized as not-for-profit. In certain U.S. states, businesses that provide professional services requiring a state professional license, such as legal or medical services, may not be allowed to form an LLC but may be required to form a similar entity called a professional limited liability company (PLLC).