The `std::out_of_range` exception in C++ is part of the Standard Library and is used to indicate that an operation has attempted to access an element outside the valid range of a container, such as an array or vector. This exception helps programmers identify errors related to invalid indices, ensuring that code behaves predictably and safely. When a `std::out_of_range` exception is thrown, it typically occurs during operations like accessing an element with an index that exceeds the container's size. Handling this exception allows developers to implement error-checking mechanisms, improving the robustness of their applications and preventing crashes due to invalid memory access.