Types are fundamental to all programming in C++.

Each type defines the storage requirements and the operations that may be performed on objects of that type. The language provides a set of fundamental built-in types such as int and char, which are closely tied to their representation on the machine’s hardware. Types can be nonconst or const; a const object must be initialized and, once initialized, its value may not be changed. In addition, we can define compound types, such as pointers or references. A compound type is one that is defined in terms of another type.

The language lets us define our own types by defining classes. The library uses the class facility to provide a set of higher-level abstractions such as the IO and string types.