Marshall Brain's favorite word is "fascinating." He uses it for nearly everything.

The newest book by Malcolm Gladwell? "Fascinating." Uploading human memory into computers? "Fascinating." How stone lithography works? "Fascinating."

It's an apt description for Brain himself.

The 45-year-old entrepreneur founded HowStuffWorks.com eight years ago because he wanted to write about how cars work. It became one of Time magazine's "50 Best Web Sites" in 2002. He sold it that year.

Since then, the Cary resident has become a writer and futurist. Now he zips around the country to talk about robots, business and technology -- he has even been on "Oprah" -- yet sometimes he forgets his own age.

"I have just a general memory problem," Brain says. "My whole writing career is dedicated to the fact that I don't have a memory."

Brain writes a lot.

He writes about the future at the site www.marshallbrain.com/ robotic-nation.htm.

He writes about robots on his blog, marshallbrain.blogspot.com. He writes about himself on MySpace.com -- though he confesses he doesn't quite get it.

In all, he maintains 15 Web sites on various subjects and answers hundreds of e-mail messages a day. In a typical week, more than a million people read what he has to say.

Remember: Robots!

He has curious ideas. By 2050, Brain envisions a world where robots will be ubiquitous and people will be able to live in computer-generated virtual worlds.

In his online essay "Robotic Freedom," he writes, "We are standing right now on the threshold of the robotic era. Once robots start arriving in the job market in significant numbers ... they have the potential to dramatically change the world economy."

If Brain is not writing, it's usually because he's traveling. He may be giving a talk about humans becoming integrated with computers -- as he did last week in Vermont. Or at a local school demonstrating scientific principles, for example, toting along a heavy scuba diving rig as a visual aid to help explain how it works.

Lee Ann Obringer, 40, a staff writer for HowStuffWorks.com, says Brain's ability to explain things is amazing. "At first, he's a little bit quiet," she says with a laugh, "but once you get him talking. ..."

A wall of books -- he has read all of them -- dominates his office in the suburban Cary home that he shares with his wife and four children.

At 5-foot-10 and 200 pounds, Brain looks boyish with his tousled, sandy hair. To fall asleep at night, he reads comics.

"It's a way of clearing the palette," he explains.

Brain is a huge fan of writers Isaac Asimov and Carl Sagan, but lately he has been enthralled by Malcom Gladwell, best-selling author of "The Tipping Point" and "Blink."

"If I could cause myself to write in a different way, Malcom Gladwell would be my model," Brain says. "I admire him because he's taking stuff that's esoteric and academic and he's making it palatable to everyone."

Brain's development

Brain was born in California, where his father was an engineer who worked on the Apollo space program and the transit systems of San Francisco and Atlanta. He was 14 when his father died.

Shortly after the death, Brain's mother dragged him to Big Brothers Big Sisters. One mentor was a businessman who planted an entrepreneurial seed in the young Brain.

It would be years before Brain's business sense was able to sprout.

He graduated from college in New York in 1983, then came to N.C. State University to pursue a doctorate. In 1992, he left the program to start a software training and consulting company, Interface Technologies, in Raleigh.

Dr. Alan Tharp, Brain's master's degree adviser, says he was an outstanding communicator and computer science teacher at NCSU. It was there that Brain met his wife, Leigh.

He was different, she says, because of his "outside of the box" ideas. "One thing I noticed when I first met him was that he always thinks big," she says. "He's constantly asking himself, 'How can this change the world?' "

One step toward that goal was HowStuffWorks.com, which he started in 1998 working from his kitchen table. Brain calls it the classic Internet success story.

"I would write articles about how stuff works and put them on the Web for free. My idea was that these articles would help people understand all the incredible stuff that surrounds us today."

The popularity of the Web site allowed Brain to write and sell a slew of "How Stuff Works" books.

He sold the company in 2002 to Atlanta-based Convex Group, run by WebMD.com founder Jeff Arnold.

Brain "is a very active spokesperson for us, he's always on CNN or Fox," Arnold says.

The book royalties and the sale made Brain a millionaire, but he only recently gave up his 1995 Ford Ranger for a new Jeep Liberty; partly because he got a "fantastic" deal on it. "You can get three rebates," he exclaims.

Brain prefers faded jeans to suits and enjoys fishing with his children -- ages 4 to 8 -- as well as taking them to McDonald's.

Currently, he is trying to shed 25 pounds and, true to form, he is writing about it. See the "How Dieting Works" section on www.howstuffworks.com.

He hasn't left the how-to business at all. He is working on another book: a primer about how to make a million bucks.

"He's never complacent," Leigh Brain says. "No matter what awards he gets, he's already thinking about what's next."