Idenitifying pins in my code. which pin is which? I'm new to arduino and knnow nothing about electronics.
How do I idenitify which pin is which in the coding?
eg- I have a pin on my esp8266 "D3"... how would I reference that in the code?
If you select the right board in Tools menu, you can use constants corresponding to labels.

pinMode(D3, OUTPUT);
digitalWrite(D3, LOW);