If a function template parameter has type T&& for a deduced type T, or if an object is declared using auto&&, the parameter or object is a universal reference.

std::move performs an unconditional cast to an rvalue, while std::forward casts its argument to an rvalue only if that argument is bound to an rvalue.

For std::unique_ptr pImpl pointers, declare special member functions in the class header, but implement them in the implementation file.

Compared to new, make functions eliminate source code duplication, improve exception safety, and, for std::make_shard and std::allocate_shared, generate code that’s smaller and faster.

Potential use cases for std::weak_ptr include caching, observer lists, and the prevention of std::shared_ptr cycles.