How Python Generators Work: Lazy Execution, Memory Efficiency, and send()

Python generator functions differ from regular functions by returning an iterator object immediately without executing any code inside the function body. Execution only begins when the caller explicitly requests a value using next(), and the generator suspends at each yield statement, resuming from that exact point on the next call. Once a generator has yielded all its values it becomes permanently exhausted, and a new generator object must be created to iterate again. Generator expressions offer a memory-efficient alternative to list comprehensions by computing values on demand rather than storing the entire sequence upfront. Advanced usage includes the send() method, which allows callers to pass values back into a suspended generator, enabling two-way communication during iteration.