## Definition A metaphor in engineering that describes a system with unknown internal workings. *Noun.* > Because `sort()`'s implementation is hidden, it's a black box to me. I just have to trust that it works! ## Characteristics - A metaphor for a system; - an example of [[abstraction]]; - conveys that the system's internal workings are hidden, unknown, or deliberately ignored; - conveys that the only things that matter are the system's inputs and outputs; and - a matter of perspective—a black box for one person may be a [[white box]] for another. ## Examples ### Large language models (LLMs) LLMs are black box systems as we do not know how their internal logic works. This is a result of the way in which LLMs are "grown, not crafted"[^1]. ### Human brains We observe stimulus and response but we don't fully understand the mechanisms in between. ### Library subprograms At the point of use, library subprograms are black boxes as their internal workings are unknown. When you use `print()`, you don't care about exactly how it makes text appear on the screen—just that it does. ## Non-examples ### Open source code [[open source|Open source]] code is, by definition, not a black box. Instead, it is a white box as the internal workings are visible and can be inspected—even if you personally choose not to look, the logic is available. ### A simple, documented function A function like `add()` isn't a black box—the mechanism connecting input to output is fully known and trivial, so there's no hidden internal workings. ```python def add(a, b): """ Parameters: a: int b: int Produces: s: the sum of a and b """ return a + b ``` ## Notes [^1]: Eliezer Yudkowsky and Nate Soares, If Anyone Builds It, Everyone Dies (Vintage, 2025), loc. 615.