Can a function be called without being defined first?

Within the context of programming, a function must typically be defined before it can be called. This means that the interpreter or compiler needs to understand what the function is and what it does prior to executing any code that references it. If a function call is encountered before its definition, the environment will not have any information about the function and will throw an error indicating that the function is not recognized.

This concept is fundamental in programming languages like JavaScript, Python, and many others, where function hoisting or definition order often dictates the correct flow of execution. In those scenarios, the order of operations is crucial, and defining the function first ensures that when you attempt to call it, the system understands what the call is meant to execute.

While there are some exceptions in certain languages where functions can be declared after being called (like through hoisting in JavaScript with function declarations), in general practice and for a solid understanding of how functions work, they should be defined before they are invoked. Crystallizing this understanding helps in creating error-free and well-structured code.