A device is an instrument or apparatus made for a specific purpose. In technology, the word covers everything from smartphones to thermostats to industrial sensors. A device has a function. It may be simple or complex, connected or standalone, worn or installed.

The term is deliberately broad. A USB drive is a device. A pacemaker is a device. A smart speaker is a device. What they share is a designed purpose and a physical form. Software alone is not a device. It needs hardware to run on.

Categories of devices

• Input: keyboards, mice, scanners
• Output: monitors, printers, speakers
• Storage: hard drives, USB sticks, memory cards
• Network: routers, modems, switches
• Mobile: phones, tablets, wearables

The number of connected devices keeps growing. Cisco estimated over 30 billion by 2023. Each one needs power, security, and management. The Internet of Things is really an internet of devices, each with its own vulnerabilities.