Hardware is the physical components of a computer or electronic system. You can touch it. You can drop it. The processor, memory, motherboard, hard drive, keyboard, monitor, and cables are all hardware. Software tells hardware what to do. Without software, hardware is inert. Without hardware, software has nowhere to run.

Hardware comes in many forms. Consumer devices like phones and laptops are hardware. Industrial controllers and medical devices are hardware. Even the tiny microcontroller in a microwave is hardware. The term covers anything with a physical presence in a computing system.

Major categories

• Processing: CPU, GPU, microcontroller
• Memory: RAM, cache, registers
• Storage: SSD, hard drive, flash
• Input: keyboard, mouse, touchscreen
• Output: monitor, printer, speaker
• Networking: router, modem, network card

Hardware ages. Software updates can extend its life, but eventually it becomes too slow or incompatible. Moore's Law predicted transistor density would double every two years. It held for decades. Now it is slowing. Hardware progress is harder than it used to be.