What is the difference between C++11, C++14,...?

I just begin to learn C++ and I encounter many C++ code online that seems pretty old fashion. For example, most of them still do something like:

std::cout << "Hello there";

While in my text books, we just do:

cout << "Hello there";

I also notice that there are several version of C++ like C++11 and C++14.

I want to ask: What is the major difference between them, what version does most online sources write on and what is the newest version?

Thank you