What are the main purposes of using std::forward and which problems it solves?

Question

In perfect forwarding, std::forward is used to convert the named rvalue references t1 and t2 to unnamed rvalue references. What is the

Answer 1

A point that hasn't been made crystal clear is that static_cast handles const T& properly too.
Program:

#include 

using namespace std;

void g(const int&)
{
    cout << "const int&\n";
}

void g(int&)
{
    cout << "int&\n";
}

void g(int&&)
{
    cout << "int&&\n";
}

template 
void f(T&& a)
{
    g(static_cast(a));
}

int main()
{
    cout << "f(1)\n";
    f(1);
    int a = 2;
    cout << "f(a)\n";
    f(a);
    const int b = 3;
    cout << "f(const b)\n";
    f(b);
    cout << "f(a * b)\n";
    f(a * b);
}

Produces:

f(1)
int&&
f(a)
int&
f(const b)
const int&
f(a * b)
int&&

Note that 'f' has to be a template function. If it's just defined as 'void f(int&& a)' this doesn't work.