TalkBack uses touch-based gestures similar in concept to VoiceOver but with its own specific gesture set, and it is the primary way blind and low-vision users interact with Android phones, tablets, and the Chrome browser on mobile.
Given Android’s large global market share, especially outside North America and Western Europe, TalkBack testing is particularly important for any organization with an international audience, and mobile accessibility testing that only covers iOS and VoiceOver risks missing a substantial share of real-world assistive technology users.