What is the function of the “ref” keyword in C#?

In C#, the ref keyword is used to pass parameters to a method by reference. By using the ref keyword, the method can modify the value of the parameters passed to it, rather than just modifying a copy of the parameter. This allows for modifying the value of the variable passed to the method within the method, affecting the value of the variable outside the method. Therefore, the ref keyword can be used to implement bidirectional communication for passing parameters, where the method can modify the value of the parameters passed to it.