Snapchat called its augmented-reality face effects introduced in September 2015 “Lenses.”
Lenses used face detection to place animated effects over a person’s face while taking a photo or video. Early examples included exaggerated facial expressions, rainbow effects, and face-swapping-style transformations. Users typically activated them by pressing and holding on a face in the camera viewfinder.
Lenses are often confused with Snapchat’s regular filters. Filters generally add overlays such as colors, location labels, or event graphics after capture, while Lenses modify faces or the surrounding scene in real time. Snapchat later expanded the idea beyond faces with World Lenses, which added augmented-reality effects to places and objects.
The feature helped make Snapchat a major consumer showcase for mobile augmented reality. Its popularity also encouraged sponsored Lenses and later tools such as Lens Studio, which let creators and advertisers build their own effects.