Prerequisite: Pointers, References 

C and C++ support pointers which are different from most of the other programming languages. Other languages including C++, Java, Python, Ruby, Perl and PHP support references. 

On the surface, both references and pointers are very similar, both are used to have one variable provide access to another. With both providing lots of the same capabilities, it’s often unclear what is different between these different mechanisms. In this article, I will try to illustrate the differences between pointers and references. 

Pointers: A pointer is a variable that holds memory address of another variable. A pointer needs to be dereferenced with * operator to access the memory location it points to. 

References : A reference variable is an alias, that is, another name for an already existing variable. A reference, like a pointer, is also implemented by storing the address of an object. 
A reference can be thought of as a constant pointer (not to be confused with a pointer to a constant value!) with automatic indirection, i.e the compiler will apply the * operator for you. 

Pointers and references are two fundamental concepts in C++. They both provide a way to indirectly access the value of a variable, but they differ in some important ways.

A pointer is a variable that holds the memory address of another variable. It is declared using the * operator. A pointer can be reassigned to point to a different memory location and can be set to a null pointer value. To access the value of the variable pointed to by the pointer, the * operator is used.

A reference, on the other hand, is an alias for an existing variable. It is declared using the & operator. Once a reference is created, it cannot be made to refer to another variable. A reference must be initialized when it is declared, and it cannot be set to a null reference value. To access the value of the referenced variable, the reference itself is used.

Another important difference between pointers and references is that pointers can be used to iterate over arrays, whereas references cannot. Also, pointers can be used to implement dynamic memory allocation and deallocation, while references cannot.

In terms of performance, references are generally faster than pointers because they eliminate the need for an additional level of indirection. However, pointers can be more flexible in certain situations, such as when dealing with data structures or passing parameters to functions.