PC and Arduino

You have come to the place to learn about connecting an Arduino to other devices, whatever software is running on those other devices. The Arduino can "talk", (transmit or receive data) via a serial channel, so any other device with serial capabilities can communicate with an Arduino. It doesn't matter what program/programming language is driving the other device.

You can either use the Arduino's "main" serial port, the one it uses when you "talk" to it to program it, or you can leave that channel dedicated to programming (and the development environment's serial monitor), and use two other pins for an extra serial link dedicated to the external device.

Some programs (like Flash) don't have native serial capabilities. They can still communicate with Arduino through an intermediary which, like a "translator", enables them to talk to each other.

This tutorial describes various programs to deal with this.