What happens if you call a function that does not exist?

When a function that does not exist is called, it results in an error. This is because the programming environment searches for the function definition to execute the code associated with that function. If it cannot find a matching definition, the program cannot proceed with execution of that function, leading to a runtime error. This prevents the program from executing further unless the error is handled or corrected.

It's important to always ensure that functions are defined before they are called in the program to maintain smooth execution and prevent such errors. In programming, careful management of function definitions and calls is crucial for successful code operation.