Before you can start your company, you'll need to understand the industry within which you will be operating. Different industries have different threats and opportunities you'll need to consider: Pending legislation or a difficult regulatory environment? High/low barriers to entry? Major competitors and market concentration? Standard cost structure? All of these are issues you will address via your industry research.
Often industry data is organized by classification system codes established by the U.S. government: NAICS or SIC codes. Knowing the code(s) for your industry can be extremely useful in your research. For more information on NAICS, visit the Census Bureau NAICS page. For more information on SIC codes, visit the Department of Labor SIC page. Or ask one of the librarians for help.