This is not meant to be a comprehensive list of resources, far from it, just enough to get you over the hump of having no idea where to start.
- Arduino had its beginnings in the Master's thesis of a Colombian student in the Interaction Design Institute Ivrea. That project consisted of a development platform designed around Atmel's ATmega128, which itself is designed around Atmel's AVR architecture. That Master's project went on to become the Wiring project, which, after being adapted to the less expensive ATmega8 processor, was forked as the Arduino project. Arduino is probably best classed as a single-board microcontroller. Arduino the Documentary is a short film that tells the story of how Arduino came to be.
- Raspberry Pi
- Similar in concept, the Raspberry Pi, developed by the Raspberry Pi Foundation, is designed around processors using the ARM architecture, also found in most smart phones. Because even the least powerful version of this platform can accommodate a keyboard and monitor, and because their processors are powerful enough to run application software on full-blown operating systems, the Raspberry Pi should be thought of as a single-board computer.
This really only scratches the surface of what's available, but these two platforms both have vibrant ecosystems, which means an abundance of related resources. For any particular project, there might be another platform which is better fit for purpose, but the smaller the ecosystem surrounding any such alternative the more expertise that is likely to be required to use it.
This has been a very short installment, but we'll come back to the topic of the processing component of the sense-think-act cycle.
Next we enter the beginning of that cycle with a more detailed discussion of sensors, exploring the collection of information about environments composed of soil, plants, and critters.