Instagram said Monday that it's added another 100 million monthly users. That brings the photo-sharing app to 800 million monthly active users, up from 700 million in April, according to Carolyn Everson, vice president of global marketing solutions at Facebook, who spoke at an Advertising Week event in New York City.

Five hundred million of those are daily active users, the company said. That means that Instagram is still ahead of rival Snap in terms of users, based on Snap's last report. Snap said in August that it had .

The announcement from -owned Instagram further solidifies Facebook as one of the most dominant companies in online advertising, posing a challenge for underdogs. Time spent watching video on Instagram is up more than 80 percent year over year, the company also said on Monday, and four times as many videos are being produced every day on Instagram compared with a year ago.

Instagram also said that it has doubled the number of advertisers on its platform since March, growing its advertiser base to 2 million.