Measuring Influence

Gwyneth Paltrow on Stella McCartney

Leonardo DiCaprio on Van Jones

Quincy Jones on John Legend

Gordon Brown on Barack Obama

Arnold Schwarzenegger on Edward Kennedy

Oprah Winfrey on Michelle Obama

Alec Baldwin on Tina Fey

Michael Bloomberg on The View Ladies

Michael Moore on Bernie Madoff

Bill Gates on Jeff Bezos

Jeb Bush on Leonard Abess

J.K. Rowling on Gordon Brown

The word influence is derived from an ancient astrological term describing the power of the stars to affect the destiny of human beings. The definition has changed a bit over the centuries, but influence remains a mysterious force and a difficult one to measure. That's part of the reason the TIME 100 list of the most influential people in the world is so diverse and eclectic. How do you gauge the influence of a molecular biologist vs. that of a politician, weigh the relative impact of a tennis player and a fashion designer or an architect and a minister? You can't, of course, and we don't try. But we look for people whose ideas, discoveries, talent and, yes, power shape and transform our world. These are our modern stars who shape our destiny.

Many of the people on our list made the cut on the basis of social innovation, activism or an ability to change people's lives for the better. But not everyone. Bernie Madoff is on this year's list. So is one of the world's most notorious drug dealers. In the end, we tried to cover as much ground as possible--and to match our subjects with pitch-perfect writers: Oprah Winfrey on Michelle Obama, Ted Turner on T. Boone Pickens (and vice versa), Roger Federer on Tiger Woods, Angelina Jolie on Cambodian activist Somaly Mam. All bring passion and expertise to their portraits. Some, like filmmaker Michael Moore on the aforementioned Madoff, bring a note of polemics too.

The impresario of this year's list--and alchemist of the magical pairings--was deputy managing editor Josh Tyrangiel, whose day job is presiding over TIME.com He was assisted by numerous section editors as well as tireless deputy chief of reporters Andrea Dorfman. Deputy art director D.W. Pine and associate art director Chrissy Dunleavy created the strong and elegant design. Pine also oversaw the wonderful gatefolds that invite you to dive deeper into the TIME 100. Our photo team, led by deputy picture editor Dietmar Liz-Lepiorz, Amy Hoppy and Diana Suryakusuma, delivered a collection of arresting portraits.

In an annual tradition, we've given the back page of this issue to columnist Joel Stein, who has, in his inimitable fashion, ranked the TIME 100 on the basis of their influence on him. And in what we hope will become an annual tradition, this year we'll attempt to harness the power of these leaders, thinkers, artists, titans and heroes to address some of the most important issues of the day. We will be convening groups of current and former TIME 100 honorees for a series of conversations focusing on subjects like the economy and the environment. You'll be hearing more about the outcome of those conversations in TIME and on TIME.com in the months ahead.

Richard Stengel, MANAGING EDITOR