Like the other comments say it’s an app which prompts users to post a picture at “the same” time. Its not actually the same time due to timezones.

The idea behind it is that you don’t ge to pick the perfect time for a pic when you’re at that great location or you’re looking especially cute. This means you’ll get an insight in the real life of someone.

Practically that means you’ll just see a lot of pictures of your friends whilst they’re laying on the couch 2 feet deep in a bag of crisps.