While　perovskite　solar　cells　have　skyrocketed　in　recent　years　to　power　conversion　efficiencies　competitive　with　those　of　silicon　and　thin-film　photovoltaics,　the　lagging　behind　stability　stands　in　the　way　of　commercialisation.　In　this　review,　we　discuss　the　reasons　and　factors　that　induce　the　degradation　in　photovoltaic　performance　of　perovskite　solar　cells,　and　furthermore,　we　summarise　the　most　promising　strategies　to　enhance　the　lifespan.　We　show　that　each　component　of　the　device,　including　the　charge　selective　contacts,　perovskite　layer,　and　electrodes,　can　be　engineered　to　reduce　the　influence　of　heat,　UV　light,　oxygen,　moisture　and　their　synergetic　effect　on　the　operating　lifetime　of　devices.　We　conclude　that　inorganic　contacts　and　inorganic　perovskite　compositions　are　the　most　promising　direction　toward　stable　perovskite　solar　cells.