[Maxatar]

In science randomness is usually used to abstract over a large number of possible paths that result in some outcome without having to reason individually about any specific path or all such paths.

It does not have to mean something inherently non-deterministic or something that can't be modelled, although it certainly is the case that if something is inherently non-deterministic then it would necessarily have to be modelled randomly. Modelling things as a random process is very useful even in cases where the underlying phenomenon has a fully understood and deterministic model; a simple example of this would be chess. It's an entirely deterministic game with perfect information that is fully understood, but nevertheless all the best chess engines model positions probabilistically and use randomness as part of their search.

[srean]

> Modelling things as a random process is very useful even in cases where the underlying phenomenon has a fully understood and deterministic model

Output of of a pseudorandom generater is a good example.