What is Fortune 500?

Legal Definition
The Fortune 500 is an annual list compiled and published by Fortune magazine that ranks 500 of the largest U.S. corporations by total revenue for their respective fiscal years. The list includes public companies, along with privately held companies for which revenues are publicly available. The concept of the Fortune 500 was created by Edgar P. Smith, a Fortune editor, and the first list was published in 1955. The Fortune 500 is more commonly used than its subset Fortune 100 or wider list Fortune 1000.
-- Wikipedia
Legal Definition
The 500 largest US manufacturing companies are listed based on reported revenue, display several corporate information reportings. It is an annual ranking by Fortune magazine.