Use auto && for the ability to modify and discard values of the sequence within the loop. (That is, unless the container provides a read-only view, such as std::initializer_list, in which case it will be effectively an auto const &.)
    Use auto & to modify the values of the sequence in a meaningful way.
    Use auto const & for read-only access.
    Use auto to work with (modifiable) copies.

#include<iostream>
#incllude<vector>
using namespace std;

int main() {
   vector<int> vec(10);       // Auto deduce type to be iterator of a vector of ints.
   for(auto it = vec.begin(); it != vec.end(); vec ++)
   {
      cin >> *it;
   }
   return 0;
}

auto n=1;
// this will make the type int, and you can't change trough the program;
cout << n;
// OR
auto n="how you doin'";
cout << n;