ESP8266
- It has just enough memory and processing power to handle a few tasks while communicating back and forth with other devices over WiFi.
- It has a limited number of IO pins
- It runs both 3.3v and 5v
- It can connect via USB or simply draw it power from a USB port.
- It can be used to take sensor readings or switch a relay - all remotely.
- Best thing is, they run about $8 each!
- There are boards that only have the ESP8266 that are cheaper, but I use the ones that are NodeMCU for convenience.
