How does RAII prevent resource leaks in C++?

Resource acquisition is initialization binds a resource’s lifetime to an object whose destructor performs cleanup. Stack unwinding destroys fully constructed local objects when exceptions propagate, making cleanup reliable without duplicated error branches. Use standard owners such as std::unique_ptr, std::vector, and lock guards instead of manually pairing allocation and release throughout a function. Destructors should not throw during unwinding. RAII handles more than memory: it can release locks or file handles, provided the wrapper accurately represents ownership and is not copied in a way that duplicates release responsibility.