MicroPython
MicroPython is a version of Python 3 made to run on microcontrollers. It fits in hundreds of kilobytes and runs directly on the chip, with no operating system underneath.
How it works
You flash MicroPython onto the board once, like any firmware. After that the board runs Python files from its own filesystem, and gives you a Python prompt, the REPL, over USB. You can type Python at the board and see the result at once.
MicroPython keeps most of the Python language and part of its standard library. It adds modules for
hardware: machine for pins, I2C, SPI and PWM, network for WiFi, and asyncio for running several tasks at once.
from machine import Pin
led = Pin(15, Pin.OUT)
led.on()
The limits
Microcontrollers are limited. A board typically has hundreds of kilobytes of RAM, and MicroPython itself uses some of it. Python is also much slower than C, though fast enough for most sensing, switching and networking jobs.
Where Thingstudio fits
Thingstudio runs on top of MicroPython. It installs a runtime onto the board, and turns each flow you deploy into MicroPython code. The function node runs your own MicroPython. See installing MicroPython to get it onto your board.
If you already use MicroPython, see if you know MicroPython for how Thingstudio uses your board.
More
Further reading: