What is the 3D touch on Iphone 6s?

What is the 3D touch on Iphone 6s?

It is a pressure sensitive screen that will do different actions depending on how much pressure you put on the screen.

You have to try it on your own so you can get a feel as to what it can do.
It's useful for bringing up shortcuts. So for example, if you wanted to record a video, you can force press into the Camera app and choose "Record Video" instead of having to manually change the recording settings. It's mostly for shortcuts.

IMO, it's a bit gimmicky.

It's where the screen senses pressure (if you press the screen harder) and it can be used for different functions