A couple summers ago, some friends and I took a trip upstate, hunting for watering holes. Eventually, we found the mother of all swimming spots: a towering waterfall in the middle of the woods, cascading down into a basin of ice-cold, green-black water. Jeffrey, our self-appointed swimming expert, jumped right in; I tiptoed around on some stones, worried about a long skinny red thing I suspected was a water snake. But Jack, a 21-year-old college student, hung back on the shore, distracted by something on his phone. A cute boy he’d hung out with a few times back in the city was in area for the weekend as well, and Jack seemed determined to send him the perfect shirtless selfie. He scaled a bank of dirt and engaged in a prolonged face-off with his phone camera, trying to capture the ideal ratio of shadow to light.

Later, he’d tell me that they’d been sending photos back and forth since the day we set off. Their conversations followed a script that was completely alien to me, but seemed perfectly understood between the two of them: one would send a photo, then the other would say how hot the photo looked, and send a photo back. Jack’s camera roll set off a minor explosion in my brain. I felt like he and the boy were speaking a language that I didn’t speak, and that I hadn’t even really known existed.

As the weekend unfolded, the purpose of their photo-swapping would become clear: an indication, after some time apart, that the flirtation between them was back on. “I think at one point he sent me a selfie that was too cute,” Jack said, of how the other boy opened the floodgates. “It was a clear-intention selfie, the kind where you can tell there were 10 to 15 outtakes of this one picture that captures the kind of cute they like to feel.” Things reached something of a climax on the last night of the trip, when Jack jumped in a car at 1 a.m. to go meet up with him a couple of towns over (they made out a little, but he was back at our cabin before morning). When I asked him about it later, he said that sending and receiving come-hither photos forms a regular part of his courtship repertoire — though he typically reserves full nudity for more impersonal hook-up contexts, like Grindr.

Hearing this, I felt my age; I am more than half a decade older than Jack. I am not an avid selfie-taker, nor have I ever sent or received a sexy photo. Texts, emails, and even regrettable late-night Myspace messages have been an indispensable part of dating for me since college, but I’d always thought of the act of undressing as something that happened in person — the offline culmination of all the messaging and waiting and second-guessing, the moment that proved whatever was going on between me and another person was a “thing.” It’s not that I feel frightened or scandalized by the idea of sending or receiving a nude; it just hasn’t been something that ever happened. I’m not sure why that is, but my best guess is that it has something to do with the fact that I came of age — romantically, sexually — before taking quality photos of yourself with your phone was something people were able to do.

But age can’t possibly tell the whole story; the internet is littered with the body parts of countless high-profile adults, from Kim Kardashian’s Kanye-summoning white bathing-suit selfie to Anthony Weiner’s debatably election-losing penchant for sending underwear hard-ons. While studies of nude-swapping are few and far between, a 2014 analysis of 19 surveys published in the Clinical Psychology Review suggests that contrary to most sensationalist headlines about high schoolers who do it, sending sexually explicit material from one’s phone is far less popular among adolescents than it is between adults. The number of teenagers who’ve sexted tended to hover between 10-15 percent, while for those 18 and older, it was closer to 50 percent. Another 2014 survey by McAfee, an internet security company, claimed that many as 70 percent of those between the ages of 18-24 had sent or received sexually suggestive messages, higher than any other group surveyed.

That said, I didn’t see much of a correlation between sexting and age among the women and men I spoke to for this story, who were all in their twenties and early thirties. So what’s the difference between a person who sends and receives sexy photos from a person who doesn’t? In what sorts of situations do people use nudes, and to what end?

For Rose, a 26-year-old writer, it started with a long-distance relationship. Around the time she graduated from college, she fell for a friend just as he was about to move across the country; nudes became a way of “keeping in touch” in the most literal way possible. “It was like we were having sex,” she explained. “We would send each other videos of each other finishing. It was our kind of foreplay for when we eventually hooked up.” After the relationship fell apart, she kept taking pictures — this time, in the form of meticulously art-directed self-portraits in various states of undress, which she selectively sent to men she was seeing, sometimes in the middle of the work day. “It was at a time when I was feeling particularly confident about my body and my ability to attract people,” she told me. “I have more photos from that two-year period than any other time in my life.” We were seated in her Brooklyn apartment, and as she said this, she reached under her bed and pulled out a plastic bin that contained, among other mementos, the odd acrylic canvas of a half-clothed torso or a nipple. “Sometimes I’d even paint them.”

Rose’s relationship with nudes was about as idiosyncratic as that of any of the other women I interviewed, whether they snapped and sought nudes on a regular basis or considered an unsolicited dick pic on Snapchat grounds for immediate blocking. But pretty much all of them agreed that the advent of the front-facing phone camera in the early 2010s offered women a means of sexual empowerment — allowing them to control the production and circulation of their own image, however undressed it may be.

Over email, a 32-year-old multimedia artist who sends the occasional nude photo to her husband told me she sees the practice as an empowering alternative to images typically mass-produced for the male gaze. “Personally, I used to be much more insecure about my appearance,” she said, “so I usually share selfies when I'm feeling really positive about myself and don't want to hide it. Technology allows us to author an image meant just for our partners that has just as much value as an image of a celebrity or a porn star.”

Mary, a 24-year-old writer who has never sexted in her life, said that when it comes to hooking up, sending fully clothed selfies to guys can have the same result as a nude. “On Thursday, I was hanging out at Bossa, and this dude I was texting with was like, ‘I don’t know if I want to come out.’ But then I sent him a selfie, and he was there in 30 minutes.”

It can be hard to tell where the selfie ends and the nude begins, especially when both can be used to get someone to go to bed with you. But like the photos that we post for our friends on Instagram, nudes are bound up in all sorts of power dynamics; they practically demand compulsory action on the recipient’s part, whether it’s a compliment or a late-night visit. Still, the way we interface with nudes seems to tell us more about our own relational script than anything inherent to the practice. Whereas Rose told me she feels more in control when she is the one to initiate a nude-sending marathon, her friend Greta, a 23-year-old grad student, said she usually only feels comfortable sending them after being asked. “I think it’s because I like to be chased — and then seeing this kind of power, and then being able to fulfill a desire,” she told me. “Even with just being hit on, I like to be approached more than I like to approach. I have a massive fear of rejection.”

And then there are those who gravitate to the pursuer role. Steven, a 30-year-old media professional I spoke to, told me the pleasure for him was all in the requesting. “I think I get a rush out of asking for it,” he said. “It’s not like I go back to the image again and again. It’s the immediate moment of getting it — this ownership thing.” In the context of one long-distance relationship he had, he said it functioned as a way of making sure he and his boyfriend “were still in it.” But he’s also met guys who seem to get a similar thrill from sending nude photos to near strangers — one, notably, started sending him dick picks out of the blue after they worked together on a professional project. “It felt like it was more about him than it was about me,” Steven said. “I remember seeing at one point that one of them was timestamped from a different day, so I knew it was something he was sending to other people.”

Like many of today’s dating practices, it’s possible that the digital nude was a courtship technology pioneered by the queer community. In her 2016 book Labor of Love: The Invention of Dating, Moira Weigel credits the invention of the heterosexual singles’ bar in the 1950s to the founder of TGI Friday’s, who reportedly got the idea from visiting LGBTQ speakeasies around New York. Grindr, which allows users to upload a library of photos to a geolocated messaging app, predates Tinder by about three years. One 27-year-old gay man, Brian, told me that in his experience, people who use Grindr typically cut to the chase pretty quickly, usually as a way of pre-selecting who they’d like to chat with more — or hook up with.

Still, it’d be inaccurate to suggest that something as complex and idiosyncratic as online courtship strategies can be reduced to a matter of sexual preference. Brian said many of his Grindr interactions don’t involve any nudes at all, and Steven, the serial-requester, said he’d never, ever send one to someone he wasn’t already dating seriously. By contrast, Greta, the 23-year-old grad student who says she doesn’t like sending nudes unless she’s asked, said she ends up messaging them to strangers on Instagram all the time.

Of course, part of the excitement of sending nudes is the element of risk, whether you’re worried about accidentally popping up on a lover’s screen during a work meeting, or unwittingly ending up on the internet for all the world to see. But you don’t have to be a victim of revenge porn to experience the heart-stopping anxiety a nude can induce. Over the phone, Weigel pointed out that requesting a nude photo takes guts. “In a way, articulating your desire, or asking for something, seems almost as exposing as a photograph,” she said. This line of thinking was consistent with many of the people I spoke to, and certainly with my own experience: the idea of sending a nude photo, or asking for one, can feel way more intimate than actual sex.

With so many variables at play, it can be easy to see why the lore of contemporary dating is littered with horror stories of post-photo radio silence and grainy photographic evidence of things we never asked to see. “When it comes to what people find sexual, for some this can make them feel powerful, for others it can make them feel very vulnerable and unsafe,” explained Dr. Ali Mattu, a clinical psychologist and assistant professor at Columbia University Medical School. “I don’t think you’ll find any clear through-line there, beyond that this maps on to larger beliefs and thoughts that people have about sex.”

Our nude photo use also maps onto beliefs that we have about gender — particularly when it comes to heterosexual relationships. Two straight men I interviewed said that though they’d exchanged nude photos with women on occasion, they’d never initiated the photo-sending themselves, partly for fear of coming off as sexually threatening. “If a woman showed her boobs to me on the street, I wouldn’t be afraid of her assaulting me,” said a 29-year-old comic from New York. “Whereas if a guy shows his penis on the subway, I can understand how a woman would feel uncomfortable — just based on the track record, you know? So I think it’s maybe different for a girl to send an unsolicited nude photo, because there aren’t issues of safety that come into it. Maybe that’s a double standard, but I don’t think double standards are always bad.”

From his work as a researcher and clinician, Dr. Mattu says he’s come to believe that the politics of the nude photo line up pretty perfectly with the politics of consent. “When we think about consent, he explains, “it’s two people actually having a discussion and saying, ‘Hey, I’m wondering if this is something you’re comfortable with, if this is something you’d want to do.’ If both people in the relationship do actually consent to sharing these types of photos or videos with each other, it can actually really strengthen the satisfaction the person has in the relationship.”

Dr. Mattu has a point: as we live an increasing amount of our lives online, it’s inevitable that we’ll have some of the same difficult conversations we have when we’re lying in bed together via text. As Mattu sees it, trouble arises when we use the distance of digital communication as an excuse to avoid having those discussions completely — presenting only the most carefully curated versions of ourselves to each other, blindly hoping we’ll end up on the same page. In other words, depending on the way we use them, nudes can be just as much of a way of exposing ourselves to other people as a way of preventing them from truly seeing us. At one point in my conversation with Rose, this realization led me to venture, somewhat lazily, that nothing beats meeting someone in real life, feeling chemistry, and figuring out the nuances of each other's bodies. Her phone lit up with a text message, and she picked it up, frowning: “But does that even happen anymore?”