PostSecret doesn’t advertise. Aside from appearing in an All-American Rejects video, Dirty Little Secret in 2005, the project doesn’t get much play in mainstream media.

Still, nearly a quarter billion people have visited postsecret.com — a site filled with reader-submitted postcards adorned with artwork and personal secrets.

What I find most intriguing about the project is that its popularity stems almost entirely from person-to-person interaction, rather than from a clever marketing strategy.

For example, I discovered PostSecret when I saw a book by Frank Warren, the project creator, on a friend’s coffee table. I’ve passed the project along to dozens of friends. Most of them have become faithful followers, as have I.

I met Warren on campus last night. At a pre-lecture radio interview, he noted the project thrives on grass-roots communication.

“I think it allows the project to keep growing,” said Warren, who stuck out on a college campus — too gray to be a student but too friendly to be a faculty member (he wasn’t above scribbling an autograph on my interview notes: “Adam — You have a lot of talent. No joke. — Frank”).

He said PostSecret doesn’t necessarily have a universal meaning. To each community member, the project means something different.

While Warren does utilize social networking to promote his events, the majority of postsecret.com viewers venture to the site without coaxing by mainstream media.

In a world where everyone — even my grandma — has Facebook, there’s something romantic about an idea that is spread through real people actually communicating with each other. That transmission is “real and authentic” Warren said.

Even the site’s restrained black background seems to underscore the point: “Let the postcards themselves do all the talking,” Warren said.