As for the core C++ language, rvalue references, lambdas and variadic templates are probably the biggest additions. Lambdas and variadic templates are optional

As for the core C++ language, rvalue references, lambdas and variadic templates are probably the biggest additions. Lambdas and variadic templates are optional, but you need to be aware of rvalue references and move semantics, which enable optimizations previously unavailable. If you write functions for which it might be advantageous to move values rather than copy them, such as transferring ownership of dynamically allocated memory from one instance of a class to another, then you should consider using rvalue references.