Crisis Text Line has received five million texts, providing a unique corpus of data. Illustration by Cristiana Coucerio; photographs: Top to Bottom: Nick Vaccaro / The Image Bank / Getty; Anna Eckold / Moment / Getty; Atsushi Yamada / Photodisc / Getty

In 2011, a young woman named Stephanie Shih was working in New York City at DoSomething.org, a nonprofit that helps young people start volunteer campaigns. Shih was responsible for sending out text messages to teen-agers across the country, alerting them to various altruistic opportunities and encouraging them to become involved in their local communities: running food drives, organizing support groups, getting their cafeterias to recycle more. Silly, prankish responses were not uncommon, but neither were messages of enthusiasm and thanks. Then, in August, after six months on the job, Shih received a message that left her close to tears for the rest of the day. “He won’t stop raping me,” it said. “He told me not to tell anyone.” A few hours later, another message came: “R u there?” Shih wrote back, asking who was doing this. The next day, a response came in: “It’s my dad.”

DoSomething.org had no protocol for anything like this, so Shih texted back with the contact information for RAINN (Rape, Abuse & Incest National Network*)*, the country’s largest anti-sexual-assault organization. But the texter indicated that she was too scared to make a phone call. “This is the right thing to do,” Shih insisted. There was no reply. “Not knowing if she was safe or had gotten help or would ever get help consumed my thoughts,” Shih told me last fall. She printed out the text messages and handed them to her boss, Nancy Lublin, DoSomething.org’s C.E.O.

“I’ll never forget the day,” Lublin said. “It was like I’d been punched in the stomach.”

That week, Lublin and Shih started work on what two years later became Crisis Text Line, the first and only national, 24/7 crisis-intervention hotline to conduct its conversations (the majority of which are with teen-agers) exclusively by text message.

Depression is common among teens, and its consequences are volatile: suicide is the third leading cause of death for Americans between the ages of ten and twenty-four. In that same age group, the use of text messaging is near-universal. The average adolescent sends almost two thousand text messages a month. They contact their friends more by text than by phone or e-mail or instant-message or even face-to-face conversations. A. T. & T. offers parents a tutorial in deciphering acronyms used by children (PIR stands for “parent in room”). For teens, texting isn’t a novel form of communication; it’s the default.

People who spent their high-school years chatting with friends on landlines are often dismissive of texting, as if it might be a phase one outgrows, but the form is unparalleled in its ability to relay information concisely. The act of writing, even if the product consists of only a hundred and forty characters composed with one’s thumbs, forces a kind of real-time distillation of emotional chaos. A substantial body of research confirms the efficacy of writing as a therapeutic intervention, and although tapping out a text message isn’t the same as keeping a diary, it can act as a behavioral buffer, providing distance between a person and intense, immediate, and often impulsive feelings. Communication by text message is halting and asynchronous, which can be frustrating when you’re waiting for a reply but liberating when you don’t want to respond. The young people who contact Crisis Text Line might be doing so between classes, while waiting in line for the bus, or before soccer practice. In addition, more than ninety-eight per cent of text messages are opened; they are four times more likely to be read by the recipient than e-mails. If you’re a parent, you know that, even if your son does not text you back about where he is, he has read your message. If you are a distressed teen or a counsellor, you know that what you say will be read.

A person can contact Crisis Text Line without even looking at her phone. The number—741741—traces a simple, muscle-memory-friendly path down the left column of the keypad. Anyone who texts in receives an automatic response welcoming her to the service. Another provides a link to the organization’s privacy policy and explains that she can text “STOP” to end a conversation at any time. Meanwhile, the incoming message appears on the screen of Crisis Text Line’s proprietary computer system. The interface looks remarkably like a Facebook feed—pale background, blue banner at the top, pop-up messages in the lower right corner—a design that is intended to feel familiar and frictionless. The system, which receives an average of fifteen thousand texts a day, highlights messages containing words that might indicate imminent danger, such as “suicide,” “kill,” and “hopeless.”

Within five minutes, one of the counsellors on duty will write back. (Up to fifty people, most of them in their late twenties, are available at any given time, depending upon demand, and they can work wherever there’s an Internet connection.) An introductory message from a counsellor includes a casual greeting and a question about why the texter is writing in. If the texter’s first message is substantive (“My so-called boyfriend is drunk and won’t stop yelling at me”), the counsellor echoes the language in order to elicit additional details (“I’m so sorry to hear that. Can you tell me a little more about what your so-called boyfriend is saying?”). If the incoming message is vague (“Life sucks. I’m freaking out”), the reply will be more open-ended, while gently pressing for greater specificity (“So what’s going on tonight?”). An average exchange takes place over a little more than an hour, longer if there is the risk of suicide.

Counsellors are trained to put texters at ease and not to jump too quickly into a problem-solving mode. Open-ended questions are good; “why” questions are bad. Also bad: making assumptions about the texter’s gender or sexual orientation, sounding like a robot, using language that a young person might not know. Techniques that are encouraged include validation (“What a tough situation”); “tentafiers” (“Do you mind if I ask you . . . ”); strength identification (“You’re a great brother for being so worried about him”); and empathetic responses (“It sounds like you’re feeling anxious because of all these rumors”). The implicit theory is that in a conversation people are naturally inclined to fill silences.

It is important to type carefully. In text messages sent to friends, typos can be an indication of intimacy. But a typo appearing on the cell-phone screen of a distressed teen-ager can undermine the sense of authority he’s looking for. “You have to train yourself not to hit that return button automatically,” a sixty-year-old counsellor from California told me. (Crisis Text Line counsellors are free to give a real or assumed first name to people who text in.) It is also regarded as a mistake to embrace teen-age patois too enthusiastically. One volunteer told me that she tries not to use acronyms. “I sometimes worry that it would come across as too ‘Oh, I got you!’ ” she said. Neutral language allows the texter to feel anonymous. These people have contacted a stranger for a reason. They aren’t looking for friendship.

Often, the conversations are about minor-seeming problems—fights with friends, academic pressure from parents—and the bar for helpfulness is quite low. “A lot of times, when chatting with young people, it’s clear that they just need someone to listen to them,” one counsellor told me. “Sometimes it’s obvious. They’ll say, ‘Thanks for listening. Nobody ever does that,’ and at other times it’s less explicit; they just want to get everything out, and they provide you with a very, very detailed account.”