What is a "Bindi" in the novel, Theory of Bastards?

The Bindi is a forehead implant that a person can use to look up information or seek entertainment, experiencing it through their Lenses and EarDrums and controlling what they see via voice command or hand gesture. The Bindi blinks when it is in use, so other people can tell when someone is distracted or unavailable for conversation. Many Bindis feature logos that reveal the relative wealth of the owner.