How do you provide feedback for blind people or low-vision people for clicks on a touch screen? What technology is used? I heard iPhone provides this kind of feedback; what it is?
You can go for haptic feedback. Provided the user has enabled haptic feedback in settings.
Well, other people already said it although in a very simple way, so here it goes again (credits to them): what you're looking for is called Haptic Feedback, which is one of the components of a Haptic Interface
A haptics interface is a system that allows a human to interact with a computer through bodily sensations and movements. Haptics refers to a type of human-computer interaction technology that encompasses tactile feedback or other bodily sensations to perform actions or processes on a computing device.
Haptic Technology is so common and popular it replaced the original name this technology had, which is kinesthetic communication. However, now is more common to hear the word Haptics (one word, plural) for this technology
While Haptics is NOT only for visually impaired, but has a lot of uses in VR, gaming, medical and high tech devices, this technology is often used in devices for the visually impaired as well as devices for people with some neurological disorders.
More important: Haptics is so common that as an example, it's what is used for a simple "incoming message" vibration, or some gaming console peripherals, so its use is really wide and growing every day.