> Heap allocated vs. stack/statically allocated. `str` is very rarely stack allocated, and often points into a heap-allocated `String`. Further, there's an opt

> Heap allocated vs. stack/statically allocated. `str` is very rarely stack allocated, and often points into a heap-allocated `String`. Further, there's an optimization on the table that will let `String`s point to static allocations. The distinction is rather owned vs borrowed. A `String` is in charge of the memory it uses, so it can grow it by reallocation, free it when it goes out of scope, etc. A `str` is not in charge of the memory it uses- it's only a pointer into some memory that something else owns, whether that's a static allocation or a `String` or some other data structure.