How to show a heart — the universal symbol of love — has shifted on the internet over the years, driven by new technology.

Sheera Frenkel, who reports on social media from San Francisco, watched dozens of videos on how to make <3 shapes for this article.

Feb. 14, 2023

Take your middle fingers and bend each down at the bottom knuckle at a steep angle. Then take your index fingers and arch them down to touch. The rest of your hands curl out of sight.

The resulting shape — a heart — is unmistakable. And for Gen Z, it’s become one of the few cool ways to express love online today.

For as long as people have connected digitally, there have been ways to show love, with the heart being the most universal. The distinctive curves-and-point symbol was birthed in the 14th century when the Italian physician Guido da Vigevano wrote a treatise on the dissection of a heart and drew it in the now-familiar shape.

How people make hearts, and the mediums they are shared through, have shifted as new technologies have emerged. In the late 1800s, operators of the first electrical telegraphs used Morse code to send each other love messages by tapping out the word “heart.”

As the internet age dawned in the 1990s, heartlike images constructed with letters and numbers began catching on in AOL chat rooms. In the 2010s, a red heart was one of the first emojis developed.

Over the past decade, as social media has become increasingly visual with photos and videos, teenagers have used their hands and bodies to fashion heart symbols to post on Instagram and TikTok. The ways they bend their wrists, fingers and joints have become increasingly complex as they seek out unique ways to say “I love you.”

“It’s hard to say ‘I love you’ without it feeling cringe,” said Quinn Sullivan, 21, a college student and TikTok creator from College Station, Texas. “We’re always looking for a new way.”

Here’s how the language of hearts has changed online over the years.

In the chat room

In AOL chat rooms in the 1990s, text ruled. So people found ways to make hearts through the keys available on their keyboards.

Two crucial ones were the < symbol and the number 3, which together made an emoticon heart <3. The keys had been used since the days of typewriters to depict the symbol, said Parker Higgins, an artist and activist who has studied the history of text encoding.

AOL also popularized a new type of art made with standard text, such as semicolons, commas and dashes, to create images known as ASCII (pronounced ass-key). These images could portray a shrug, ¯_(ツ)_/¯, or a rose, @>—>—, in a single line. But they could also take up dozens of lines to depict elaborate hearts with arrows piercing them or roses woven in.

Teenagers had to be in the know to successfully clip and save those hearts, and new ones were constantly being created, Mr. Higgins said. “People would copy and iterate on versions of the hearts by putting them in their AOL away messages or profiles,” he said.

The emoji era

As mobile phones became popular earlier this century, emojis — small images that could appear alongside text — were born. Among the first to be drawn was a red heart, created in 1999 by a Japanese artist, Shigetaka Kurita.

Heart emojis did not become widely available until 2010 when a Google software team petitioned to get emojis recognized by the Unicode Consortium, a nonprofit that functions like the United Nations in maintaining text standards across computers. Once the group recognized the emojis, they became widely available on mobile devices, and then were quickly adapted by social media companies like Facebook.

Today, the red heart is one of the most popular emojis. It was the second most used in the world in 2019 and 2021, according to polls by the Unicode Consortium, beaten only by the “crying/laughing” face, which teenagers have since declared is not cool. (The consortium does not have a poll for 2022.)

“The red heart is the most O.G. emoji,” said Jennifer Daniel, the head of the emoji subcommittee at the Unicode Consortium. “We now have a lot of variations, like blue, green and purple hearts. We have broken hearts and Cupid hearts. But the red heart emoji has a distinct meaning that conveys something lovely across the world.”

TikTok shapes

There are acceptable ways of showing hearts on social media now — and ways that are not. It’s often determined by your age.

“If you want to know around how old someone is, but you don’t want to ask them directly, ask them to make a heart with their hands,” said Julia Carolan, 25, a social media influencer from New York, in a TikTok video last year.

Over the video’s next 21 seconds, Ms. Carolan demonstrated that if someone formed a heart with all the fingers on both hands, it meant that person was “a millennial … an adult.” Only Gen Z, she said, makes hearts using just the middle and index fingers, as if it were a secret code.

The video, which has been liked more than 40,000 times, is one of hundreds on TikTok, Instagram, YouTube and other social media sites that discuss the right way to make a heart with your fingers.

“What’s funny is that I can barely do the Gen Z heart with my hands. Maybe it’s because I’m almost a millennial myself,” Ms. Carolan said in an interview. “The thing now, with TikTok and these videos, is that you’re really putting yourself, your face and body out there. Whatever you are doing, especially if it is showing love, has to feel authentic.”

In some regions, people have their own ways of making hearts to post on social media. In parts of Asia, for instance, hearts are formed by placing the thumb and index finger together, in a pinching motion.

Every year brings a new, trendy way for teenagers to create heart shapes to post online, said Mr. Sullivan, the TikTok creator.

“Part of it is the exclusivity, especially in the beginning, of just a small group of people knowing what the new symbol or hand movement is,” he said. “The moment it becomes too big, it becomes cringe.”

But what is old can also become new again. There’s been a resurgence recently of “vintage hearts” in videos, like the emoticon <3, Mr. Sullivan said.

“Like everything vintage, it’s coming back,” he said.