It's not a stupid question! The short answer is: the compiler doesn't care. An array of type [T; N] (where T is the type of the elements and N is the length of

It's not a stupid question! The short answer is: the compiler doesn't care. An array of type [T; N] (where T is the type of the elements and N is the length of the array) can be allocated on the stack or in the heap (using Box<T>, as stated in sibling comments). If you access it by value, it will be copied as-is, so be careful with large arrays! You mostly access them behind a reference, but in that case, the type of the reference will be &'a [T; N] where 'a is the lifetime of the referent value. The type system by itself doesn't actually care whether the value lives in heap or stack.