Before Twitter allowed photo tagging, users would have to mention the people in the photo in the tweet itself. This meant that users' precious 140 characters were used to tag people. But the new feature allows users to tag up to 10 people in photos, useful for crowded selflies, and won't count toward the 140 character limit for each tweet.
Users will also be able to pack more images into a tweet with a new collage option that attaches four photos to one tweet. After selecting the images, Twitter will arrange them in a tile layout and make it into a rectangular image. Previously, this had to be done using third-party apps.
Users have the option of going into Settings and deciding who can tag them in an image.
Image tagging is not a new feature. Tagging is already available on Facebook, with the company expected to release an auto-tagging system that will have a near-perfect accuracy.
Social media companies have been quickly adopting features made popular by competitors. Facebook last year added clickable hashtags. When Twitter added short 6 second video on its Vine service, Instagram, owned by Facebook, was quick to add short 15 second videos to its service.