In this paper we introduce a novel gaze tracking system called FreeGaze, which is designed for the use of everyday gaze interaction. Among various possible applications of gaze tracking system, Human-Computer Interaction (HCI) is one of the most promising fields. However, existing systems require complicated and burdensome calibration and are not robust to the measurement variations. To solve these problems, we introduce a geometric eyeball model and sophisticated image processing. Unlike existing systems, our system needs only two points for each individual calibration. When the personalization finishes, our system needs no more calibration before each measurement session. Evaluation tests show that the system is accurate and applicable to everyday use for the applications.