运算符重载的问题，求助

#include "iostream"
using namespace std;
class Counter
{
public:
    Counter(){value=0;}
    Counter(int i){value=i;}
    Counter operator++();
    Counter operator++(int);
    Counter operator--();
    Counter operator--(int);
    void display() {cout<<value<<endl;}
private:
    unsigned value;
 };
Counter Counter::operator++()
{
    value++;
    return*this; //这个是什么意思？*this 是指哪个？
}
Counter Counter::operator++(int)
{
    Counter temp;
    temp.value=value++;
    return temp;
}
Counter Counter::operator--()
{
    value--;
    return*this;
}
Counter Counter::operator--(int)
{
    Counter temp;
    temp.value=value--;
    return temp;
}
int main()
{
    Counter n(10),c;
    c=++n;
    cout<<"前缀++运算符计算结果:"<<endl;
    cout<<"n=",n.display();
    cout<<"c=",c.display();
    c=n++;
    cout<<"后缀++运算符计算结果:"<<endl;
    cout<<"n=",n.display();
    cout<<"c=",c.display();
    c=--n;
    cout<<"前缀--运算符计算结果:"<<endl;
    cout<<"n=",n.display();
    cout<<"c=",c.display();
    c=n--;
    cout<<"后缀--运算符计算结果:"<<endl;
    cout<<"n=",n.display();
    cout<<"c=",c.display();
return 0;
}