On Thursday, Instagram launched photo tagging, the feature that fueled Facebook’s early growth. New Instagram iOS and Android updates rolling out now let you tag any person or brand in your own photos, which then automatically show up in the “Photos Of You” section of their profile. You get notified when you when you’re tagged, can require approvals before photos hit your profile, and have the option to detag yourself. [Note that if you’re not seeing version 3.5 of Instagram when you go to download the updates, you may have to wait a few minutes for your cluster of the App Store or Google Play to populate with the new version.] Instagram tells me a year of work went into building the new tagging and Photos Of You section. Until now, people just @mentioned each other in the comments of photos as a hack.