Ƙarfe wani abu ne dake, idan aka shirya shi, da polished, ko fractured, sai yazama mai karfi, kuma yana daukar wutar lantarki da zafi sosai. Karfe dai za'a iya zamar dashi zuwa falle, ko kuma zuwa waya. Karfe ka iya kasancewa daga chemical elements kamar iron, ko alloy kamar stainless steel.