Twitter users on mobile devices can now tag people in photos and upload multiple images to form a collage.
The capabilities come with an update to Twitter's iOS and Android apps that it started to roll out Wednesday, Twitter said.
To tag photos, you can now select a photo, tap on "Who's in this photo," and from there type in the person's full name or @username. When the photo is tweeted, the tags appear next to the photo, letting others navigate to the tagged user's profile.
People who are tagged will receive a notification, and users can restrict who can tag them in their settings.
Twitter is also adding the ability to share up to four photos in a single tweet to create a collage. That's starting to roll out on the iPhone today and is coming soon to Android and twitter.com. "Whether you're on iPhone, Android or twitter.com, you can view Tweets with multiple photos," Twitter said.
The moves step up the rivalry between Twitter and Facebook, which took photo tagging mainstream, and whose facial recognition technology can perform the function automatically.
Facebook's Instagram app also allows tagging, something it rolled out last year.
Twitter has been gradually adding more support for photos and video in its apps. Late last year it started showing photo previews directly in the Twitter feed, though some users complained it creates clutter.