on start and forever Blocks

What is a Loop?

Two blocks are loaded by default when you open a new project in MakeCode, the on start and forever blocks. These blocks are displayed below:

Together, these blocks help you manage how your micro:bit behaves when it starts and during its operation. The differences between these blocks are explained below:

on start Blocks

The on start block contains code that runs once, right when you turn on or reset your micro:bit. It’s perfect for setting things up, like displaying a welcome message or setting initial values.

forever Blocks

The forever block, on the other hand, contains code that runs repeatedly in a loop as long as the micro:bit is on. This is great for tasks that need to keep happening, like blinking an LED or checking if a button is pressed.