The evolution of active regions (AR) from their emergence through their long decay process is of fundamental importance in solar physics. Since large-scale flux is generated by the deep-seated dynamo, the observed characteristics of flux emergence and that of the subsequent decay provide vital clues as well as boundary conditions for dynamo models. Throughout their evolution, ARs are centres of magnetic activity, with the level and type of activity phenomena being dependent on the evolutionary stage of the AR. As new flux emerges into a pre-existing magnetic environment, its evolution leads to re-configuration of small-and large-scale magnetic connectivities. The decay process of ARs spreads the once-concentrated magnetic flux over an ever-increasing area. Though most of the flux disappears through small-scale cancellation processes, it is the remnant of large-scale AR fields that is able to reverse the polarity of the poles and build up new polar fields. In this Living Review the emphasis is put on what we have learned from observations, which is put in the context of modelling and simulation efforts when interpreting them. For another, modelling-focused Living Review on the sub-surface evolution and emergence of magnetic flux see Fan (2009). In this first version we focus on the evolution of dominantly bipolar ARs.

活性区（AR）从出现到长期衰变过程的演变对于太阳物理学至关重要。由于大规模通量是由深层发电机产生的，观测到的通量出现特征和随后的衰减特征为发电机模型提供了重要的线索和边界条件。在整个进化过程中，AR 是磁活动的中心，活动现象的水平和类型取决于 AR 的进化阶段。当新的通量出现在预先存在的磁环境中时，其演变导致小规模和大规模磁连通性的重新配置。 AR 的衰变过程将曾经集中的磁通量散布到不断增加的区域。尽管大部分通量通过小规模抵消过程消失，但大规模 AR 场的残余物能够反转两极的极性并建立新的极场。在这篇《生活回顾》中，重点放在我们从观察中学到的东西，在解释它们时将其置于建模和模拟工作的背景下。另一篇关于地下演化和磁通量出现的以建模为重点的生活评论，请参见 Fan (2009)。在第一个版本中，我们重点关注占主导地位的双极 AR 的演变。