Why is a $\frac{C}{C}++$ program divided into multiple source files $($modules$),$ and why do they use distinctive filename extensions such as $.$Cpp and $.$h$?$

What is the difference between a pointer and reference?

What is the function of "const" and what are some practical applications?

Summarize what function overloading is and when to use it$.$

Describe the difference between a using declaration and a using directive.