Weak references are Awesome in Python

Python's weakref module lets you hold references to objects without preventing garbage collection. The tutorial covers the core problem (strong references in caches keeping objects alive indefinitely), then walks through practical solutions: weakref.ref for non-owning references, proxy objects as transparent alternatives, WeakValueDictionary for self-cleaning caches, WeakKeyDictionary for attaching metadata to objects whose lifecycle you don't control, and WeakSet for tracking active objects. Key caveats include which built-in types don't support weak references (lists, dicts, integers, strings, tuples) and the need to grab a strong reference before using WeakValueDictionary entries.