The R-CNNs are awesome works on object detection, which demonstrated the effectiveness of using region proposals with deep neural networks, and have become a state-of-the-art baseline for the object detection task. In this blog post I'll make a brief review of the R-CNN family - from R-CNN to Mask R-CNN, and several related works based on the idea of R-CNNs. Implementation and evaluation details are not mentioned here. For those details, please refer to the original papers provided in the References section.