Lithium metal batteries (LMBs) are among the most sought-after battery chemistries for high-energy storage devices. However, LMBs always undergo uncontrollable lithium deposition, relatively lower Coulombic efficiency (CE), severe side reactions, and limited power output, which impede their practical applications. In the last 40 years, numerous efforts have been made to solve these issues, ranging from theoretically modeling the lithium dendrite growth behavior to experimentally modifying the lithium metal anode. This article provides an overview of LMBs and its main challenge—dendritic lithium growth. First, the advantages and disadvantages of LMBs are discussed compared with the state-of-the-art lithium-ion batteries, in which the lithium dendrite growth and fast CE decay are extensively considered. Specific characterization techniques are also summarized to understand the growing behavior of dendritic lithium and anode surface chemistry. To understand the fading mechanisms of LMBs, numerous models and hypotheses are carried out to predict the solid electrolyte interphase (SEI) formation, ionic electromigration, and finally dendritic growth behavior. From the insights of the abovementioned theoretical basis, methods concerning on suppressing lithium dendrites and improving the cell CE are categorized as the electrolyte additives, structural electrolyte development, new battery operation mode, multidimensional composite electrode design, and so on. Finally, future directions are given that are expected to drive progress in the development of LMBs.