**Highlights**
- Support Twins ([989](https://github.com/open-mmlab/mmsegmentation/pull/989))
- Support a real-time segmentation model STDC ([995](https://github.com/open-mmlab/mmsegmentation/pull/995))
- Support a widely-used segmentation model in lane detection ERFNet ([960](https://github.com/open-mmlab/mmsegmentation/pull/960))
- Support A Remote Sensing Land-Cover Dataset LoveDA ([1028](https://github.com/open-mmlab/mmsegmentation/pull/1028))
- Support focal loss ([1024](https://github.com/open-mmlab/mmsegmentation/pull/1024))
**New Features**
- Support Twins ([989](https://github.com/open-mmlab/mmsegmentation/pull/989))
- Support a real-time segmentation model STDC ([995](https://github.com/open-mmlab/mmsegmentation/pull/995))
- Support a widely-used segmentation model in lane detection ERFNet ([960](https://github.com/open-mmlab/mmsegmentation/pull/960))
- Add SETR cityscapes benchmark ([1087](https://github.com/open-mmlab/mmsegmentation/pull/1087))
- Add BiSeNetV1 COCO-Stuff 164k benchmark ([1019](https://github.com/open-mmlab/mmsegmentation/pull/1019))
- Support focal loss ([1024](https://github.com/open-mmlab/mmsegmentation/pull/1024))
- Add Cutout transform ([1022](https://github.com/open-mmlab/mmsegmentation/pull/1022))
**Improvements**
- Set a random seed when the user does not set a seed ([1039](https://github.com/open-mmlab/mmsegmentation/pull/1039))
- Add CircleCI setup ([1086](https://github.com/open-mmlab/mmsegmentation/pull/1086))
- Skip CI on ignoring given paths ([1078](https://github.com/open-mmlab/mmsegmentation/pull/1078))
- Add abstract and image for every paper ([1060](https://github.com/open-mmlab/mmsegmentation/pull/1060))
- Create a symbolic link on windows ([1090](https://github.com/open-mmlab/mmsegmentation/pull/1090))
- Support video demo using trained model ([1014](https://github.com/open-mmlab/mmsegmentation/pull/1014))
**Bug Fixes**
- Fix incorrectly loading init_cfg or pretrained models of several transformer models ([999](https://github.com/open-mmlab/mmsegmentation/pull/999), [#1069](https://github.com/open-mmlab/mmsegmentation/pull/1069), [#1102](https://github.com/open-mmlab/mmsegmentation/pull/1102))
- Fix EfficientMultiheadAttention in SegFormer ([1003](https://github.com/open-mmlab/mmsegmentation/pull/1037))
- Remove `fp16` folder in `configs` ([1031](https://github.com/open-mmlab/mmsegmentation/pull/1031))
- Fix several typos in .yml file (Dice Metric [1041](https://github.com/open-mmlab/mmsegmentation/pull/1041), ADE20K dataset [#1120](https://github.com/open-mmlab/mmsegmentation/pull/1120), Training Memory (GB) [#1083](https://github.com/open-mmlab/mmsegmentation/pull/1083))
- Fix test error when using `--show-dir` ([1091](https://github.com/open-mmlab/mmsegmentation/pull/1091))
- Fix dist training infinite waiting issue ([1035](https://github.com/open-mmlab/mmsegmentation/pull/1035))
- Change the upper version of mmcv to 1.5.0 ([1096](https://github.com/open-mmlab/mmsegmentation/pull/1096))
- Fix symlink failure on Windows ([1038](https://github.com/open-mmlab/mmsegmentation/pull/1038))
- Cancel previous runs that are not completed ([1118](https://github.com/open-mmlab/mmsegmentation/pull/1118))
- Unified links of readthedocs in docs ([1119](https://github.com/open-mmlab/mmsegmentation/pull/1119))
**Contributors**
- Junjue-Wang made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/1028
- ddebby made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/1066
- del-zhenwu made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/1078
- KangBK0120 made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/1106
- zergzzlun made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/1091
- fingertap made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/1035
- irvingzhang0512 made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/1014
- littleSunlxy made their first contribution in https://github.com/open-mmlab/mmsegmentation/pull/989
- lkm2835
- RockeyCoss
- MengzhangLI
- Junjun2016
- xiexinch
- xvjiarui