In C++, a class is a user-defined data type that holds its own data members and member functions, which can be accessed and used by creating an instance of that class. A class is like a blueprint for an object, and instances of a class data type are known as objects.

A C++ class has data and functions as its members, also called member variables and member functions, respectively. These members are declared to be either publicly or privately accessible using the public, private, and protected access specifiers. By default, access to members of a C++ class is private, meaning that private members are not accessible outside the class and can only be accessed through methods of the class. Public members, on the other hand, form an interface to the class and are accessible outside the class.

In summary, a class in C++ is a user-defined data type that holds its own data members and member functions, which can be accessed and used by creating an instance of that class. It is like a blueprint for an object, and instances of a class data type are known as objects.