`const_cast` is a type of casting operator in C++ that allows you to add or remove the `const` qualifier from a variable. This is useful when you need to modify a variable that is originally defined as `const`, or when you want to pass a `const` object to a function that requires a non-const reference. However, using `const_cast` should be done with caution, as modifying a `const` object can lead to undefined behavior if the object was originally defined as `const`. The primary purpose of `const_cast` is to enable the manipulation of `const` and `volatile` qualifiers in C++. It is one of the four casting operators in C++, alongside `static_cast`, `dynamic_cast`, and `reinterpret_cast`. While `const_cast` can be helpful in certain scenarios, it is generally recommended to avoid unnecessary casts and to design your code in a way that respects the `const` correctness principle, ensuring that `const` objects remain unchanged.