What does static typing ensure in a programming language?

Static typing in a programming language ensures that variable types are determined at compile time. This means that when you write your code, you specify the types of variables upfront, and the compiler checks for type correctness before the program runs. This can help catch errors early in the development process by ensuring that variables are used in a manner consistent with their defined types.

For instance, if a variable is declared as an integer, the static typing system will prevent operations that involve assigning a string value to that variable, thereby reducing potential runtime errors. This contrasts with dynamic typing, where variable types can change during runtime, allowing more flexibility but increasing the risk of type-related errors becoming apparent only during execution.

By identifying any mismatches in data types before running the program, static typing promotes greater reliability and maintainability in the code.