I can't understand this part

Question

#include <iostream>
using namespace std;

int main()
{
int a, b;
int sum;
cout << "Enter a number \n";
cin >> a;
cout << "Enter another number \n";
cin >> b;
sum = a + b;
cout << "Sum is: " << sum << endl;

return 0;
}

Someone explain what is sum is and why it was used ?

Answer 1

Sum is an additional variable that is used for adding other two input variables a&b.
You can do this if you don't want to use Sum variable.

cout<< "Sum is:" << a + b << endl;