Operational semantics is a formal method used in computer science to define how the execution of a program proceeds. It describes the behavior of a program by specifying the rules for how each statement or expression transforms the program's state. This approach helps in understanding the meaning of programming languages by providing a clear framework for their execution. In operational semantics, the focus is on the step-by-step execution of programs, often represented using transition systems or abstract machines. This allows for a precise description of how different constructs, such as loops and conditionals, affect the program's state over time, making it easier to reason about program behavior and correctness.