`std::accumulate` is a function in the C++ Standard Library, specifically found in the `numeric` header. It is used to compute the sum (or other operations) of a range of elements in a container, such as an array or vector. The function takes three main arguments: the beginning and end of the range, and an initial value for the accumulation. This function can be customized to perform various operations beyond addition by providing a binary operation as an additional argument. For example, you can use it to calculate the product of elements or concatenate strings, making `std::accumulate` a versatile tool for data processing in C++.