Public versus Private
Public companies sell shares on a stock exchange (e.g. NYSE) and they have specific requirements to disclose information to their shareholders and the public. Public companies are required to file quarterly earning reports and other information with the Securities and Exchange Commission (SEC). . An easy way to spot whether a company is public is the presence of a ticker symbol.
Examples of company filings the SEC
10-K Public company annual filing
10-Q Public company quarterly
Unlike public companies, private companies are not regulated by the federal government. Therefore, it is at the discretion of a private company if, and what, they want to disclose about themselves. It can be more difficult and time consuming to locate information about private companies.
Parent or Subsidiary Companies
Often you will find that a company is either a parent company of a subsidiary company. A subsidiary is a company whose parent is a majority shareholder. Both the parent and subsidiary are separate entities and independent of one another.
Keep in mind that it is often difficult to find detailed information about subsidiaries. Often, the best source is the parent company's annual report or 10K.
NAICS (North American Industry Classification System)
The North American Industry Classification System (NAICS) is the standard used by Federal statistical agencies in classifying business establishments for the purpose of collecting, analyzing, and publishing statistical data related to the U.S. business economy. Similar industries are grouped tother under the same number.