A Member is to a Limited Liability Company (LLC) the same as a Shareholder is to a Corporation. They are both owners of the business. An LLC Member can have a broad range of duties ranging from managing the day-to-day affairs of the LLC to doing nothing. Most LLC Members have voting powers. The duties and obligations are usually specified in the LLCs Articles of Organization. Most states do not require a list of Members as part of their LLC filing requirements.
For more information about LLCs refer to this page: How to Form a LLC Online.