Users can opt to show exactly how old they are on their profile page

Twitter wants to know people’s birthday — so they can let their followers know, show them a balloon animation, and give them more personalised ads.

The social network has launched an option to let people add their birthday in the “Edit profile” settings. Once it’s added, users can show the information to the public or their followers.

The feature will be opt-in for all users, so it won’t be shown unless the option is chosen. Users can choose who to show it to, as well as letting people decide whether they want to show the year they were born, or just the date.

But whatever options are chosen in the privacy settings, the birthday seems to be shared with advertisers. A note in a support document about the change indicates that advertisers will be able to use the information to make their advertising more “relevant”.

“If you choose to add your birthday to your profile, it will be displayed to the audience that you’ve chosen. It will also be used to customize your Twitter experience,” the document reads. “For example, we will use your birthday to show you more relevant content, including ads.”

Twitter allows advertisers to select specific details about who sees which ads, with the aim of making them more effective. It pulls together information like who users follow, what they tweet, what they search for and where they are to target posts.

Comments