Magnetic storms on stars manifest as remarkable, randomly occurring changes of the luminosity over durations that are tiny in comparison to the normal evolution of stars. These stellar flares are bursts of electromagnetic radiation from X-ray to radio wavelengths, and they occur on most stars with outer convection zones. They are analogous to the events on the Sun known as solar flares, which impact our everyday life and modern technological society. Stellar flares, however, can attain much greater energies than those on the Sun. Despite this, we think that these phenomena are rather similar in origin to solar flares, which result from a catastrophic conversion of latent magnetic field energy into atmospheric heating within a region that is relatively small in comparison to normal stellar sizes. We review the last several decades of stellar flare research. We summarize multi-wavelength observational results and the associated thermal and nonthermal processes in flaring stellar atmospheres. Static and hydrodynamic models are reviewed with an emphasis on recent progress in radiation-hydrodynamics and the physical diagnostics in flare spectra. Thanks to their effects on the space weather of exoplanetary systems (and thus in our search for life elsewhere in the universe) and their preponderance in Kepler mission data, white-light stellar flares have re-emerged in the last decade as a widely-impactful area of study within astrophysics. Yet, there is still much we do not understand, both empirically and theoretically, about the spectrum of flare radiation, its origin, and its time evolution. We conclude with several big-picture questions that are fundamental in our pursuit toward a greater understanding of these enigmatic stellar phenomena and, by extension, those on the Sun.

恒星上的磁暴表现为光度在持续时间内发生显着的、随机发生的变化，与恒星的正常演化相比，这种变化很小。这些恒星耀斑是从 X 射线到无线电波长的电磁辐射爆发，它们发生在大多数具有外部对流区的恒星上。它们类似于太阳上被称为太阳耀斑的事件，影响我们的日常生活和现代技术社会。然而，恒星耀斑可以获得比太阳更大的能量。尽管如此，我们认为这些现象在起源上与太阳耀斑非常相似，太阳耀斑是由于潜磁场能量在与正常恒星尺寸相比相对较小的区域内灾难性地转化为大气加热而造成的。我们回顾了过去几十年的恒星耀斑研究。我们总结了耀斑恒星大气中的多波长观测结果以及相关的热和非热过程。回顾了静态和流体动力学模型，重点关注辐射流体动力学和耀斑光谱物理诊断的最新进展。由于它们对系外行星系统的空间天气的影响（从而影响我们在宇宙其他地方寻找生命的过程）以及它们在开普勒任务数据中的优势，白光恒星耀斑在过去十年中重新出现，成为一种具有广泛影响力的现象。天体物理学的研究领域。然而，关于耀斑辐射的光谱、其起源及其时间演化，我们在经验和理论上仍有很多不了解的地方。最后，我们提出了几个宏观问题，这些问题对于我们更好地理解这些神秘的恒星现象以及太阳上的现象至关重要。