When we draw a face, there are usually 5 steps. Look at the pictures below.
We have special ways to draw the nose, the eyes and the mouth in the right place of a face. Every face is different. Your face may have a long nose, big eyes and a small mouth. Those make it your face, not the other's. That's a good thing for us to remember different faces.
With the help of the scientists, computers are learning to do this too. Face Recognition Programs(人脸识别程序) use the eyes, ears and other things of a face to match them to a person. The computer first finds(找出) the eyes, ears, and the mouth on a face. Then it finds out how they relate(联系), and it will stay the same(to a computer) no matter you are happy or sad.
Things like how long your nose is and how big your eyes are don't change much as you get older. That makes them useful for the computer to know you. The computer remembers all the faces. If there's a match, it recognizes you. So be careful, you have no way to go if you do something bad.