The halting problem is a famous result in computer science that proves there is no general algorithm capable of deciding, for all possible programs and inputs, whether a given program will eventually stop running (halt) or run forever. In other words, some questions about program behavior are fundamentally undecidable.
In blockchain and smart-contract contexts, the halting problem illustrates why it is impossible to automatically prove every property of a Turing-complete contract. Practical systems like the Ethereum Virtual Machine use mechanisms such as gas limits to bound execution and prevent contracts from running indefinitely, even though the underlying halting problem remains undecidable in theory.
