The　electronic　and　optical　properties　of　ZnO　can　be　modified　via　the　creation　of　intrinsic　defects,　especially　oxygen　and　zinc　vacancy.　For　researchers　to　have　a　clear　understanding　of　various　defects,　we　summarize　different　methods　that　are　used　to　prepare　and　characterize　vacancy　defects.　In　fact,　vacancy　defects　can　regulate　the　Fermi　level　of　ZnO　itself　and　enrich　photogenerated　carriers,　and　then　act　as　adsorption　sites　that　are　involved　in　the　surface　adsorption　and　photocorrosion　reaction　processes.　Furthermore,　defects　function　as　a　double-edged　sword　in　regulating　photocatalytic　performance.　It　is　suggested　that　preparing　zinc　oxide　with　a　medium　concentration　of　defects　can　obtain　excellent　photocatalytic　performance.　©　2023　WILEY-VCH　GmbH.