In C++, an iterator is an object that enables traversal through the elements of a container, such as std::vector or std::list. Iterators provide a uniform way to access elements without exposing the underlying structure of the container. They can be thought of as pointers that point to elements, allowing for operations like incrementing to move to the next element. There are different types of iterators, including input iterators, output iterators, forward iterators, and random access iterators. Each type has specific capabilities, such as reading, writing, or jumping to any position in the container. This flexibility makes iterators a powerful tool in C++ programming.