There are a multitude of microcontrollers available on the market today that are well suited for IoT prototyping. For simple projects where you just want to read a sensor value and log its value in the cloud, most microcontrollers with internet access will do a great job. In more complex projects, where you need a filesystem and more features than you would typically find on a regular computer, a microcontroller might not be enough, and you may need a development board running a full-grown operating system such as the Raspberry Pi (https://www.raspberrypi.org) or Asus Tinker (https://www.asus.com/de/Single-Board-Computer/Tinker-Board/):
These development boards come with display connectors and USB ports to connect hard drives, webcams, a keyboard, or a mouse to, and are able to run programs written in various...