Lithium–sulfur (Li-S) batteries have been considered as promising candidates for large-scale high energy density devices due to the potentially high energy density, low cost, and more pronounced ecological compatibility. However, the complex Li-S conversion reactions, unsatisfactory battery performance, and unsafe metallic Li anode restrict the development of Li-S batteries to achieve commercialization. This review mainly focuses on three aspects which are the remaining challenges, recent advances, and applications in Li-S batteries. Firstly, this review portrays Li-S conversion chemistry involving the multi-step and multi-electron reaction mechanism, as well as the remaining challenges. Then, the scientific strategies and very recent advances of the cathode, electrolyte, lithium anode, and other constituent parts of Li-S batteries are detailly summed up, as well as their advantages and limitations. For the sake of promoting the Li-S batteries practicalization, next section is primarily concerned with problems, the corresponding solutions, and application scenarios of practical pouch cells. Finally, the important findings as guidelines and some future directions as trends for developing emerging Li-S batteries are briefly summarized.