Twenty years ago, people need to use manuals in order to operate a device or machine. Twenty years later, personal products can be used easily without any instructions. That is how interaction design take place in the human beings history. The level of civilization is determined by the capability of making and using tools. With better interaction design, human beings are able to use tools more freely and efficiently. Affordance, Signifiers, and Constraints. All these elements would help to create better interaction design pieces. They can let people know how to use the tool and what the tool can do. The importance of a human’s natural reaction on an object remains regarded in design. (Week 1 of Into to Interaction Design Spring 2016)