Back in the day, they'd flutter their eyelashes or share a nervous, giggly chat.
That is hardly over. But American teens are now also turning to online networks as tools for flirting, researchers reported Thursday.
Indeed, the keypads of smartphones and such are often firing off the sparks of young love, or at least like, said the study by the Pew Research Center.
U.S. teens use such media to 'like', comment on, 'friend' or joke around with someone they have a crush on, the study said.
The old-fashioned stuff of wooing still prevails but now "technology is a major vehicle for flirting and expressing interest in a potential partner," said the study.
The survey of those between the ages of 13 and 17 said only 35 percent had been in a romantic relationship, but 55 percent had flirted or talked to someone in person to let them know they are interested.
Pew found 31 percent of teens had sent flirtatious messages, 10 percent had sent photos as part of flirting and seven percent had made a video for potential partner.
"Digital platforms are powerful tools for teens for flirting, wooing, connecting with and even showing off a romantic partner," said Pew researcher Amanda Lenhart, lead author on the report.
But there is a down side: those same media can be conduits for jealousy, meddling and troubling behavior, it added.
Thirty-five percent of all teen girls said they had blocked or unfriended someone who was flirting in a way that made them uncomfortable.
Among boys, 16 percent took this step, the study said.
Pew also found 11 percent of teens who had dated had accessed a mobile or online account of a current or former partner.
And 10 percent modified or deleted their partner's or ex-partner's social media profile.
-- eight percent had sent embarrassing pictures of a current or former partner to someone else
-- four percent placed a tracking program on a partner's device without their knowledge.
"Beyond perpetrating potentially inappropriate or harmful behavior, teen daters also can be the recipients of -- possibly more serious -- controlling or potentially abusive experiences at the hands of significant others," the study authors said.
Also, more than one in five with relationship experience said partners used online media to call them names or say mean things, mostly after a relationship ended.
And 15 percent of teen daters report that a current or former partner spread rumors about them using digital platforms.
The report was based on a survey of 1,060 teens ages 13 to 17 and a parent or guardian from September 25 to October 9, 2014 and February 10 to March 16, 2015.
The margin of error was estimated at 3.7 percentage points.SHOW MORE