In the context of nRF Connect SDK/Zephyr, a board definition refers to configuration and initialization files that define the hardware characteristics and behavior of a specific development board or hardware platform.
nRF Connect SDK comes with support for a large number of boards (Development Kits, Prototyping Platforms, and Reference Designs), and it also offers the flexibility of adjusting the hardware specifications of existing board definitions through the use of devicetree overlay files and Kconfig fragments (Covered in the nRF Connect SDK Fundamentals course).
However, there are situations where we would like to create an entirely new board definition with its unique name and unique hardware specifications. This is usually the case when you have developed your schematics and own PCB for your Nordic-based product. We call this a “custom board” as the SDK itself does not provide it.
The lesson covers how to define boards in the nRF Connect SDK using Hardware Models V1 and V2. Hardware Model V1 is used in all nRF Connect SDK versions below 2.7.0. Hardware Model V2 (HWMv2) is used in nRF Connect SDK v2.7.0 and above, and it is set to replace HWMv1 completely. It is important to select the right tab at the top of the exercise pages to match the SDK version you are using.