WASHINGTON -- After Friendster came MySpace. By the time Facebook dominated social media, parents had joined the party, too. But the online scene has changed -- dramatically, as it turns out -- and these days even if you're friends with your own kids on Facebook, it doesn't mean you know what they're doing.Thousands of software programs now offer cool new ways to chat and swap pictures. The most popular apps turn a hum-drum snapshot into artistic photography or broadcast your location to friends in case they want to meet you. Kids who use them don't need a credit card or even a cellphone, just an Internet connection and device such as an iPod Touch or Kindle Fire.Parents who want to keep up with the curve should stop thinking in terms of imposing time limits or banning social media services, which are stopgap measures. Experts say it's time to talk frankly to kids about privacy controls and remind them -- again -- how nothing in cyberspace every really goes away, even when software companies promise it does."What sex education used to be, it's now the 'technology talk' we have to have with our kids," said Rebecca Levey, a mother of 10-year-old twin daughters who runs a tween video review site called KidzVuz.com and blogs about education issues.More than three-fourths of teenagers have a cellphone and use online social networking sites such as Facebook, according to the Pew Research Center's Internet and American Life Project. But Facebook for teens has become a bit like a school-sanctioned prom -- a rite of passage with plenty of adult chaperones -- while newer apps such as Snapchat and Kik Messenger are the much cooler after-party.Even Facebook acknowledged in a recent regulatory filing with the Securities and Exchange Commission that it was losing younger users: "We believe that some of our users, particularly our younger users, are aware of and actively engaging with other products and services similar to, or as a substitute for, Facebook," the company warned investors in February.Educators say they have seen kids using their mobile devices to circulate videos of school drug searches to students sending nude images to girlfriends or boyfriends. Most parents, they say, have no idea.Eileen Patterson of Burke, Va., said she used to consider herself tech-savvy. But she was shocked to learn her kids -- she has eight -- could message their friends with just an iPod Touch MP3 player. She has nine wireless devices in her home and is now shutting off her home's Wi-Fi after 9 p.m., but she describes her attempt to keep tabs on her kids' online activity "a war I'm slowly losing every day."