Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays beyond 1 GeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, SOHO, and more recently Hinode and SDO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections, electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s) of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting magnetic reconnection as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth’s ionosphere. Flare scenarios have slowly converged over the past decades, but every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions.

从十米无线电波到超过 1 GeV 的伽马射线，所有波长均可观测到太阳耀斑。本综述重点关注 EUV、软 X 射线和硬 X 射线、白光和无线电波的最新观察结果。 RHESSI、Yohkoh、TRACE、SOHO 以及最近的 Hinode 和 SDO 等太空任务广泛扩大了观测基础。他们揭示了许多惊喜：日冕源出现在色球足点的硬X射线发射之前，主要耀斑加速地点似乎与日冕物质抛射无关，电子和离子可能在不同地点加速，至少有3种不同的磁拓扑，基本特性从小耀斑到大耀斑各不相同。最近的进展还包括对耀斑能量分配、能量释放位置、能量释放场景测试和粒子加速的深入了解。观察与理论的相互作用对于推断几何形状和理清所涉及的各种过程非常重要。越来越多的证据支持磁重联是根本原因。尽管这一过程已被普遍认为是触发因素，但它如何将相当一部分能量转化为非热粒子仍然存在争议。类似耀斑的过程可能是日冕磁场大规模重组及其加热的原因。大型耀斑影响行星际空间并严重影响地球的电离层。在过去的几十年里，耀斑情景逐渐趋于一致，但每一次新的观测仍然揭示了重大的意想不到的结果，表明太阳耀斑在被发现 150 年后仍然是一个复杂的天体物理学问题，其中包括一些尚未解决的重大问题。