(FORTUNE Magazine) – Warning: Lend out this magazine and you may not get it back. It's a keeper. This issue marks the 50th appearance of what long ago became the gold standard for corporate performance, the FORTUNE 500. To celebrate 50 years of the 500, we've tried to capture in words and pictures the living, breathing truth embodied in the cold, hard numbers of our lists. They offer an unrivaled record of just how much American business and society have changed over five decades--and also of what abides. Photo editor Michele McNally pulled in stunning images from our archives and assigned the best modern shooters to bring in the here-and-now. Issue editor Jim Aley asked some of our brightest minds to provide context and insight into companies at the center of today's business story: GE, Merrill Lynch, GM, Yahoo, and more. Other writers mined the 500 for fascinating data or explored topics ranging from the top ten in 2054 to an exclusive interview with perhaps the most underrated CEO of the modern era. We then poured it all into an elegant, flexible design created for this issue by associate art director Nai Lee Lum.

If there's an overarching theme to this special issue, it's this: Innovate or die. Ultimately that ability to adapt successfully comes down to the quality of your people (a tedious cliche that has the virtue of being true). At FORTUNE our model for all things excellent happens to be the only person who was on staff when the 500 was born in 1955, editor at large Carol Loomis. What makes Carol the best? Start with this, advises her longtime friend Warren Buffett: "She understands business better than most CEOs, accounting better than most CPAs, and investing better than most investment advisors." She then reports harder than anyone and synthesizes all she's learned in simple, elegant prose. (Did I mention she's also generous with advice and a rock of integrity?) And she keeps getting better. When I asked Carol for her favorite stories over five decades, her list was heavily weighted toward the past 15 years. (This issue's entry, "The Sinking of Bethlehem Steel," is another classic.) She won't like my saying it, but her colleagues all know that the best way to keep improving this magazine over the next 50 years is to never stop thinking of Carol as our journalistic North Star.

Rik Kirkland MANAGING EDITOR