uxn is a virtual machine that runs programs written in uxntal and assembled into bytecode.

It works in a similar way to how Java ecosystem work: (1) you write Java code, (2) compile the code into bytecode, (3) which will be executed by JVM. In this way, you write code targetting the JVM and not the actual hardware, reducing the work for developers. The JVM may be implemented for a variety of machines, and if specifications are carefully followed, any program written should work for all implemented machines.

In the uxn ecosystem, uxn is the JVM and uxntal is Java.