Attributes in C++. Are they really required for programmers?

I read that C++11 has introduced the concept of attributes for example [[noreturn]] which is to indicate that the function doesn not return to the caller.

[[noreturn]] void fun() 
{
    throw std::string("Error!!!");
}

void func()
{
    fun();
}

void aTempFunc()
{
    try
    {
        func();
    }
    catch (std::string &e)
    {
        std::cout << e << std::endl;
    }
}

By looking at the example the reader can understand that the function throws an exception and call will not be returned to the func function. I am bit confused to understand what are C++ attributes and why it is required? How a programmer can really make use of these attributes?

Can someone explain in detail. Please correct me if my understanding about the attributes is wrong. Thanks.