Function Header
The function header is a crucial part of a function definition in programming. It typically consists of the function name, parameter list, and sometimes the return value. Let's discuss each of these components in detail.

1. Function Name:
The function name is the identifier that is used to call the function. It should be unique within the program and follow certain naming conventions. It is placed at the beginning of the function header and is followed by parentheses.

2. Parameter List:
The parameter list, also known as the argument list, specifies the data that the function expects to receive when it is called. It is enclosed within parentheses next to the function name. Parameters serve as placeholders for values that will be passed to the function during its execution. They can be of different data types and can have default values.

3. Return Value:
The return value is the data that a function sends back to the code that called it. Not all functions have a return value, but when they do, it is specified using the return keyword followed by the value to be returned. The return value can be of any data type or even a complex data structure.

Function Header Example:
Here is an example of a function header that includes all the mentioned components:
```
int calculateSum(int num1, int num2)
```
In this example:
- `calculateSum` is the function name.
- `int` is the return type, indicating that the function will return an integer value.
- `num1` and `num2` are the parameters of the function, both of integer type.

Conclusion:
To summarize, the function header includes the function name, parameter list, and sometimes the return value. It provides important information about the function's name, expected inputs, and potential output. Understanding the function header is essential for defining and calling functions correctly in programming.