Lithium-metal　batteries　with　high　energy/power　densities　have　significant　applications　in　electronics,　electric　vehicles,　and　stationary　power　plants.　However,　the　unstable　lithium-metal-anode/electrolyte　interface　has　induced　insufficient　cycle　life　and　safety　issues.　To　improve　the　cycle　life　and　safety,　understanding　the　formation　of　the　solid　electrolyte　interphase　(SEI)　and　growth　of　lithium　dendrites　near　the　anode/electrolyte　interface,　regulating　the　electrodeposition/electrostripping　processes　of　Li+,　and　developing　multiple　approaches　for　protecting　the　lithium-metal　surface　and　SEI　layer　are　crucial　and　necessary.　This　paper　comprehensively　reviews　the　research　progress　in　SEI　and　lithium　dendrite　growth　in　terms　of　their　classical　electrochemical　lithium　plating/stripping　processes,　interface　interaction/nucleation　processes,　anode　geometric　evolution,　fundamental　electrolyte　reduction　mechanisms,　and　effects　on　battery　performance.　Some　important　aspects,　such　as　charge　transfer,　the　local　current　distribution,　solvation,　desolvation,　ion　diffusion　through　the　interface,　inhibition　of　dendrites　by　the　SEI,　additives,　models　for　dendrite　formation,　heterogeneous　nucleation,　asymmetric　processes　during　stripping/plating,　the　host　matrix,　and　in　situ　nucleation　characterization,　are　also　analyzed　based　on　experimental　observations　and　theoretical　calculations.　Several　technical　challenges　in　improving　SEI　properties　and　reducing　lithium　dendrite　growth　are　analyzed.　Furthermore,　possible　future　research　directions　for　overcoming　the　challenges　are　also　proposed　to　facilitate　further　research　and　development　toward　practical　applications.