Set against the backdrop of his son dying in a hot car, Justin Ross Harris’ serial sexting on that day in June looks outrageous, revolting, perverse.

For some people, the police description of Harris' activities — including allegations that the 33-year-old husband texted a photo of his private parts to as many as six women — brought them face-to-face with a corner of the culture they knew only by rumor.

But many professionals who study sexual expression in the digital age will tell you that, in itself, much of what goes under the heading of sexting is not far outside the mainstream, if at all.

“Sexting is completely normal. There’s nothing inherently wrong with it as long as all parties are consenting” and of legal age, said Amy Hasinoff, a University of Colorado Denver assistant professor of communications who has studied sexting.

However, experts also stress there are dark sides to sexting that are creepy and filled with potential risks, especially among people who don’t know one another.

“It’s so depersonalized,” said Jackson Katz, co-founder of a California company that specializes in gender violence prevention. “There’s lots of dangers, especially for women meeting men they don’t know. You don’t know if that man is a rapist.”

Harris told police he left 22-month-old Cooper in the car by accident. He is charged with cruelty to a child in the second degree and felony murder. Neither charge requires proof that he purposely left Cooper in the car to kill him — although Cobb police have said they believe he did.

Trish Gates, 58, an insurance salesperson in Lilburn, had pegged Harris as guilty of deliberate homicide before the sexting bombshell exploded. The sexting was gasoline on the fire of her outrage. “I think it’s insane that he knew Cooper was in the back, and he was (messaging) all these girls,” she said.

The term sexting applies to a broad range of activities, from mildly suggestive flirtations to the most explicit descriptions and images, from the innocent and romantic to the cruel and coercive. It includes a husband sending a sexually suggestive text to his wife, young people flirting on a mobile messaging app, and people sending graphic photos of themselves to others while trolling for anonymous sex.

Often, all of those can be found on the same app or website. Police say Harris was sexting on an app called Kik, which is a free messaging site that claims millions of users. Other popular apps such as Snapchat also are used for a range of sexting behaviors.

“They are used in a lot of different ways,” said Debby Herbenick, a sexual research scientist at Indiana University. “It’s not just dating and hookups, it’s sexy texts.”

While the popular stereotype of sexting is that it is an activity dominated by young people, a recent study shows its growing popularity among other adults. The 2014 study by the Pew Research Center defined sexting as sending, receiving or forwarding sexually suggestive photos or videos on cell phones. It did not include texts containing words but no images.

The study found that 22 percent of people aged 25 to 34 said they had sent a photo or video, and 34 percent said they had received one. Among those aged 35 to 44, 11 percent said they had sent such messages and 22 percent said they had received one.

Sex and technology have always co-mingled, whether through online personal ads, phone sex or pornography. But the prevalence of mobile phones has made it easier for people to communicate and even seek casual, anonymous sex. No longer must a person look for partners at a bar or gain entry to some sex club. Indeed, defenders of sexting say many of the activities seen on these apps are no different than what goes on every weekend at the local club.

It’s not entirely clear how far Harris’ carried his activities. Police testified at his July 3 bond hearing that at least one woman told them he tried to arrange to meet for sex and another said he told her he had had affairs and his wife knew it.

In the course of his sexting, he also portrayed himself as someone unfettered by moral conventions, according to police testimony.

A woman texted Harris: “Do you have a conscience?”

He reportedly replied with a single word: “Nope.”

At present, Harris does not face any charges in relation to the sexting allegations, and virtually everything he has been accused of doing over his phone is legal. The possible exception, if police allegations are true, is sending sexually explicit messages to a 16-year-old.

In Georgia, the general age of consent is 16, but sending explicit emails, text messages or other materials to a person under 18 is illegal.

Harris attorney, Maddox Kilgore, did not respond to phone calls seeking comment.

Whatever one feels about Harris' sexual escapades, several experts said it would be a mistake to take them as evidence that he is a child murderer.

“It’s wildly speculative,” said Katz. “Lot’s of people do sexting behavior and they are not pathological and they are not psychologically different than the average person.”

However, like the three-dimensional world, the sexting realm has corners filled with violence, exploitation and perversion. “Revenge porn,” the practice of publicly posting nude images of one’s former partner following a breakup, is just one well-known example.

Harris’ alleged sexting with a girl who was 16 when their interactions began points to what experts call one of sexting’s most disturbing aspects: the ease with which young people can be ensnared and exploited. Some messaging apps are free, and while they assert age limits, a young person can lie on the membership form.

Inside the app can dwell sexual predators, sex addicts, prostitutes and others wanting to take advantage of kids. Many adolescents are conditioned by a sexting culture that fosters crass flirtation. They’re titillated by the never-ending sexting scandals involving celebrities such as Tiger Woods, Tony Parker and Billy Bob Thorton. Many don’t realize the dangers of sending off what can become a permanent, intimate image of themselves.

“They may be with a boy or a girl today, and be betrayed tomorrow,” said Catherine Steiner-Adair, a clinical psychologist and author of the book The Big Disconnect: Protecting Childhood and Family Relationships in the Digital Age. “There’s very dangerous and ugly uses of sexts.”

That is what happened to one 12-year-old Sandy Springs girl, who ran into trouble on the messaging app Snapchat. The Atlanta Journal-Constitution has a policy of not naming the victims of sex-related crimes.

The girl said she was texting with a boy about 14-years-old whom she knew, when he started asking for nude pictures of her.

After she refused, she said the boy threatened to place a photo of her face on a another’s nude body and spread that around. Fearing that, she sent him one, and proceeded to “freak out even more.”

Months later, in February of this year, the boy contacted her again, saying that unless she sent another nude photo he would spread around the one he had.

“I ran to my dad crying and told him everything,” the girl said.

Her father said he went to the police but, after the boy denied threatening the girl, no charges were brought. The girl said she learned some lessons.

“Don’t trust boys,” she said. “And don’t do something that’s not good. And if something happens, go to somebody sooner.”