DETROIT — She noticed the handsome stranger as they were boarding the overnight flight from Seattle to Detroit on the Tuesday after Thanksgiving.

Tall, about 60ish, balding beneath the baseball cap he wore and well-mannered — he let her on the plane ahead of him — she was disappointed they weren’t seated together. Later, though, in baggage claim, they chatted and he helped her with her luggage, hoisting it off the carousel. They separated without exchanging phone numbers, e-mail addresses or names.

“I feel like I blew a chance to meet somebody nice,” says Mary Garen, a 62-year-old retired special education teacher from Plymouth, who has so regretted she didn’t ask the man if he wanted to have coffee that she did something quite out of character: She placed an ad in the “missed connections” section of http://detroit.craigslist.org, the Internet bulletin board, in hopes of finding him.

“It’s so far-fetched,” Garen says. “And yet,” she adds, “I believe in karma.”

So, it seems, do lots of other people.

Craigslist, the Web’s version of want ads, covers 450 cities in 50 countries and is one of the 10 busiest Web sites in the United States.

Log on to Craigslist.org and click on wherever, and you’ll find listings for used furniture and used cars, apartment rentals and jobs.

You’ll also find the personals ads, including the missed connections ads — people looking for people they glimpsed at a bar or a grocery store or at the light at Utica Road and Metro Parkway or just about anywhere else. People seeking long-lost relatives. People seeking former sweethearts. People seeking information on a years-ago car accident. And seeking peace from a deceased parent.

While the definition of “missed connection” is a broad one, the free ads have a common thread.

Sometimes hopeful and apologetic, sometimes raunchy — pornographic images are not allowed but often words are more than adequate to provide the reader with a picture — and full of adulterous desires, they tell the stories of things that, for better or worse, went unsaid.

‘It is a long shot’

“I am looking for Wendy from Ferndale, I think you are 28. It is a long shot since I really only know you through a mutual friend, but with everything I know about you I think we could be good for each other. …”

Craigslist says it carried more than 100,000 missed connections postings in December and most of them were put up by people from the United States. Despite requests, Craigslist didn’t provide information specific to Metro Detroit, though if you look at the site, you’ll notice about 30 to 40 new local missed connections get posted every day.

The reason behind the numbers is simple, says Craigslist spokeswoman Susan Best: “Walking directly up to a person and expressing your interest in them can be a terrifying experience for many people. And perhaps a little off-putting for the person on the receiving end.

“And, in the case of missed connections, that fleeting eye contact often lingers in the person’s mind, ‘I wonder who they are? I wonder what they are like? I wonder …’ Missed connections give us a second chance. Humans love second chances.”

People hope that even if the missed connection doesn’t see the ad, someone who knows him or her will; Craigslist has a wide reach.

It’s the ninth busiest Web site in the United States and 66th busiest in the world, according to Alexa, a company that tracks Web site traffic. And, according to Craigslist, it gets 10 billion page views a month.

“It’s not really so much that I’m looking for an ad directed at myself — that’d be silly, since I hardly ever go out anywhere,” says Kat Eller, a freshman at Eastern Michigan University and avid reader of the missed connections ads.

“I like the little peeks they give me into other people’s lives. Into the way their minds work and how they feel. Ultimately, it’s nosiness.”

‘I’m also married’

“I was passing by and you smiled at me and gave me a bump with your hip … I’m older than you … you have blondish color hair, maybe 5’5” nice build, cute smile, and are very cute and sexy … hope you see this and respond… oh I’m also married … Hope you might also be looking for (no strings attached) relationship hopeful (long-term) also or just occasional adventure with an older sexy handsome man who is safe to be with in many ways. Please respond”

— man trying to find a woman he met in an unnamed bar

Craigslist isn’t necessarily the best or easiest or quickest way to find a person; there are other sites out there. But Craigslist is the one with the reach and reputation.

What makes Craigslist personals so attractive to users is that they’re free — you must be 18 years old to post, however — and they’re anonymous, two things that tend to embolden people.

“These are the same people who were evidently too shy to approach their missed connection in person,” says Robin Edelstein, a University of Michigan psychology professor who specializes in relationship issues. “So there must be something about the anonymity of the Internet that makes this seem like a safer strategy. Some of the posters were trying to find people who they saw working at a particular place, so they could certainly go back and talk to them if they really wanted.”

For married people or people who are involved in relationships, the idea of contacting someone outright is not an option. One married poster offered to talk to the newspaper — provided, of course, that his name wasn’t used — but said he’d have to call us on the sly, when his wife isn’t around. Another man said he is using Craigslist to find a woman he saw at a lecture. He didn’t approach her at the time because he was with a woman he is already dating.

For other people, contacting a person outright is too real and could mean having to deal with the possibility of rejection, says Shirley Bavonese, a relationship expert who is a founding partner at the Relationship Institute, a Royal Oak, Mich., psychological practice.

With Craigslist’s missed connections, there is no such thing as rejection. If you don’t hear from the person you’re looking for, you can easily tell yourself he or she doesn’t know about Craigslist — it’s big, but it’s still not google.com.

In fact, with Craigslist, you can tell yourself anything you want, provided other users don’t flag your ad as inappropriate and get it deleted from the site. You can contact your first love, even though you’re sleeping with your current love. You can hit on women even though you’re married. You can hit on other men even though everyone in your day-to-day life thinks you’re straight.

Craigslist is an instant, alternative universe. It’s one where you can send a message to a missed connection you don’t know and tell yourself that he or she will receive it if the relationship is meant to be. And as ridiculous as it may seem — the odds that a complete stranger will remember you are slim — you feel good. Because posting means you’ve done something to forward your cause. It gives you hope.

“It’s frivolous. It’s fun. It’s the stuff of romance novels,” says Bavonese. “That’s the draw.”

‘I miss you like crazy’

“I know you’ll never read this. I know even if (you) did it wouldn’t matter much. I think I’m writing it more to get things off my chest and go forward…The bottom line is that I miss you like crazy and I want to hold you and feel you in every way possible. I dont think thats going to happen because you’ve probably moved on and are happier now. Respond to this post if you ever see this if you have anything to say…”

—a man posting to a woman he identifies as “N”.

Craigslist doesn’t keep track of how many missed connections end up meeting — and sometimes that’s not always the point behind a posting.

Read through the missed connections ads and you’ll find a fair number that address past wrongs, people apologizing for mistreating a friend or family member. For these posters, writing is about confession and catharsis.

After class one evening, Eller, the student at Eastern, posted a note to her recently deceased mother.

Her post: “You were in the hospital bed, struggling under tubes and wires and the fever raging in your body. I was your daughter, sitting next to you … The papers were already signed to take you off of all of your support. I left, forgot to say goodnight. Our final connection, missed. I’m sorry.”

“I’ve been having some dreams about her,” says Eller, of Southgate, Mich. “I’ve been thinking about her a lot. … I felt that I needed to talk to her, I felt I missed her. …

“Where else am I going to post it? That seemed like the right place to put it. I just wanted to say it so that it had been said. … I still know that I said it too late. … It helped a little that I said it.”

A leap of faith

Aside from a couple of blind dates — fix-ups by friends — Garen, who is shy and describes herself as lacking confidence, hasn’t gotten up the nerve to do much dating in the nearly dozen years since she’s been divorced.

But recently, perhaps spurred by her empty nest — both her children have moved out of state — she’s realized she doesn’t want to spend the rest of her life alone. That she’d enjoy having a man with whom she could go to dinner, vacation and share her life with.

“I just wish somebody would just walk up to the door,” she says. “I’m not going to go to a bar. I’m not going to go to a singles thing.”

Then, on her trip home from visiting her daughter in Seattle: the man on the plane.

An episode of “Ellen” that featured a couple who met on an airplane and connected later through the Craigslist missed connections ads helped Garen get up the nerve to post on Craigslist, which she learned about from her daughter.

On Feb. 21, she wrote: “After the flight, we talked in baggage claim. You were wearing a baseball cap and had just returned from visiting your son in Seattle; I had been visiting my daughter. You said you lived in Livonia, close to my home in Plymouth. I wish I would have asked you to get a coffee since we live so close to each other. Maybe you’ll see this, and it won’t be too late!”

Garen knows that the odds are against her — she has yet to receive a response from the man from the plane and postings expire after 45 days. She also knows that many may see what she’s done as a tiny, insignificant thing, although for her, it represents a big step forward.

“Maybe he’s still thinking about me,” she says.