The ESP32 microcontroller is mounted to a breakout board with all the needed circuitry to power and program the chip and connect it to your computer. I has heaps of IO pins to connect peripherals, built-in power and control LEDs, an antenna for wi-fi signal, and other useful features. Thanks to the efforts of the Arduino community, is able to be programmed with the Arduino IDE 'langauge' through the ESP32 add-on. It has 512kB of RAM, 4MB of flash memory and features like 12 bit ADC, 8 bit DAC, I2S, I2C, touch sensor and SPI.
3.3V operating and IO voltage
5V-3.3V converter onboard for operation from USB
Arduino add-on available (installation required)
Micropython firmware available