Which of the following is NOT a feature of an Internet of Things (IoT) device?

In the context of Internet of Things (IoT) devices, the primary features typically include connectivity, sensors, and automation. Connectivity allows IoT devices to communicate with each other and with central systems over the internet, which is essential for their functioning. Sensors enable these devices to collect data from their environment, such as temperature, motion, or humidity, and play a critical role in their ability to provide information and feedback.

Automation refers to the capability of IoT devices to perform tasks without human intervention, responding to sensor data or communications dynamically and efficiently. This feature enhances their utility by streamlining processes and improving efficiency.

Manual operation, on the other hand, doesn't fit the typical characteristics of IoT devices. While some may have manual controls for user intervention, the essence of IoT is to reduce the need for constant human input, allowing for remote control and autonomous functioning. Therefore, the reliance on manual operation is contrary to the design philosophy of an IoT device, making it the correct choice for what is NOT a feature of such devices.