The stuff that makes up your computer and all it's pieces and parts. Includes things like your keyboard, your hard drive, and your modem. Usually made up of circut boards and wires.

An older forgotten meaning refers to things like hammers, 2x4's, and power tools as hardware. This is the stuff men buy in the Sears Craftsman department so that they can go home and fix things, build things, or break things they were trying to fix.