A wrapper or container class is a class, a data structure, or an abstract data type which contains different objects or collection of objects as its members.
A wrapper class is a custom object where the wrapper class properties are defined. Consider a custom object in Salesforce. It contains different fields of different data types. Similarly, wrapper class is a custom class which has different data types or properties. As per requirement, we can wrap different object types or any other types in a wrapper class.