In the past two decades, the waiting area has been widely used in many large cities in China as an effective strategy to increase the capacity of at-grade signalized intersections, especially during peak hours. Unfortunately, despite its popularity and prevalence, there does not exist any quantitative technical/design standards for formulating the implementation of waiting area and evaluating its performance. It is an unconventional design from practice and its theoretical investigation is actually after it is implemented in numerous signalized intersections. In this regard, this paper presents an overview of existing research and applications with a focus on the traffic operations and performance evaluation of the waiting area in at-grade signalized intersections. We first emphasize the design and its integration with signal phasing. Then performance analysis is introduced. This is followed by a few critical remarks and directions of the future work.