In Python object-oriented programming theory, the string representation of an instance is governed by a specific method resolution order where `__str__` serves as the human-readable delegate and `__repr__` as the primary programmer-readable fallback. The core mechanism dictates that if a custom `__str__` is not defined, the interpreter attempts to invoke `__repr__` as the default implementation, ensuring a representation is always available. This theoretical framework establishes `__repr__` as the authoritative source for object identity and state inspection, while `__str__` handles user-facing descriptions, with the latter inheriting the former's logic when absent.
Prerequisite chain context: requires Python Developer vs User Readable Strings.