Millions of U.S. teenagers shut up in their homes and receiving their education online are turning for morale support and comic relief to each other - via immensely popular video sharing apps like TikTok.

The social media platform is owned by China's ByteDance and has prompted national security concerns in Washington over fears about how it collects and shares data on U.S. users.

But for high schoolers, TikTok is just an outlet for them to share their stories. In 2019, TikTok said it had over 26 million monthly active users in the United States, over half of whom were between the ages of 16 and 24.

Users post videos that can last up to 60 seconds, appearing on phones in fast-paced feeds. While many TikToks tend to be lighthearted - dancing or lip syncing to trending songs is a common theme - they can also deal with more serious issues.

Some users say that the app - and others like it, such as Snapchat - lets them know other people are going through the same things they are and relax and laugh about it. The coronavirus and forced school vacation - labelled the "coronacation" - is the biggest trending topic on TikTok.

"How the class of 2020 is gonna graduate," jokes user @dannyrvbio, over a video showing an emoji of a student walking across a digital stage. In another popular TikTok captioned "Me pretending my screen froze bc I didn't do my project for my online class," user @zizzysizzle stutters as if she is having connection problems during a pretend video explanation to her teacher on the 1930s stock market crash.

Others advise on how to entertain yourself during quarantine, or how to stay safe. The World Health Organization has its own @who TikTok, with its experts explaining the virus and how it can affect young people in short clips.

"TikTok has really helped me get through these weeks," said 17-year-old Alison Kenny, a highschooler in the suburbs of hard-hit New York. "It's frustrating to be stuck and feel trapped... it's nice to know you aren't alone and people are struggling just as much as you."