Early-type dwarf galaxies (ETDs) are the end-points of the evolution of low-mass galaxies whose gas supplies have been extinguished. The cessation of star formation lays bare the ancient stellar populations. A wealth of information is stored in the colours, magnitudes, metallicities and abundances of resolved stars of the dwarf spheroidal and ultrafaint galaxies around the Milky Way, allowing their chemistry and stellar populations to be studied in great detail. Here we summarize our current understanding, which has advanced rapidly over the past decade owing to flourishing large-scale astrometric, photometric and spectroscopic surveys. We emphasize that the primeval stellar populations in ETDs provide a unique laboratory for studying the physical conditions on small scales at epochs beyond redshift z = 2. We also highlight the observed diversity of star-formation and chemical-enrichment histories in nearby dwarfs. These data cannot yet be fully deciphered to reveal the key processes in dwarf evolution, but the first successful attempts to pin down the sites of heavy-element production have been made.

早型矮星系（ETDs）是气体供应已经熄灭的低质量星系演化的终点。恒星形成的停止暴露了古老的恒星种群。大量信息存储在银河系周围矮球状星系和超微弱星系的分辨恒星的颜色、星等、金属丰度和丰度中，从而可以对它们的化学和恒星种群进行非常详细的研究。在这里，我们总结了我们目前的理解，由于大规模的天体测量、光度测量和光谱调查，在过去十年中取得了迅速的进展。我们强调，ETD 中的原始恒星群体提供了一个独特的实验室，用于研究红移z以外时期的小尺度物理条件 = 2. 我们还强调了在附近矮星中观察到的恒星形成和化学富集历史的多样性。这些数据还不能完全破译以揭示矮人演化的关键过程，但已经首次成功尝试确定重元素的生产地点。