CNNs Make the computer having a capability like human eyes on recognizing object(s) in an image. This is a talk for discussing the basic principle and technical details of CNNs. In an intuitive and easily understandable way, the most of concepts such as local receptive field, parameter sharing, pooling and the mechanism of feature recognition in CNNs will be shown. Also the inherent defects in CNNs will be discussed. Through this lecture, people can understand how and why CNNs can surpass the human eye in the field of image recognition.