The cognitive ability of humans depends much on the vision.'Vision'refers to the sense that receives stimulus of light through eyes.'Gaze'refers to a function of a straight line that connects the central point of the pupil and a viewpoint in the external world, and, in general, it means a straight line that connects an object that is viewed and the eyes. There are active studies on the gaze in various academic circles including'psychology'and'cognitive linguistics.'As a method to objectively analyze the gaze, studies on'eye tracking'are revitalized. A device for studies on eye tracking is an'eye tracker.'As the fields of the study expand from development and analysis of Web pages to analysis of stores, methods of traffic signal processing, transport equipment, analysis of user experiences on image contents, and marketing analysis, there occurs a greater demand for a glasses eye-tracking than that for a fixed eye tracker. This study identifies the overview and characteristics of eye tracking and presents a way for spreading studies on eye tracking.