Selecting The Correct Board - Espressif ESP8266 User Manual

D. Selecting the Correct Board
Now your Arduino IDE knows about ESP8266 boards in general. But not all the ESP8266
boards are the same; there are subtle but important differences in available Flash Memory
and how they can be programmed. The selection of the correct board also defines the names
of the GPIO pins: the designers of the NodeMCU decided to introduce a completely new
naming scheme for the pins. Instead of calling them GPIO1, GPIO2 etc they decided to give
them different numbers by using a "D"- prefix. So D0 is GPIO16, D1 is GPIO5 and so on. By
selecting a NodeMCU board you automatically have the D naming scheme available, and this
helps a lot since these names are also printed on the module board.
So, let's pick the correct board. If you bought the original Squix Starter Kit you will have to
choose a NodeMCU 1.0: Go to Tools > Board: * > NodeMCU 1.0 (ESP-12E Module) There is
a plentitude of modules available. Please make sure that you have the correct board selected
before you continue.