Explain how DFS can be implemented iteratively using a stack.

DFS can be implemented iteratively using a stack. In this approach, a stack is used to keep track of the vertices to be explored. The process involves pushing the initial vertex onto the stack, then repeatedly popping a vertex, visiting its unvisited neighbors, and pushing them onto the stack. This iterative process continues until the stack is empty, ensuring a depth-first exploration of the graph without the use of recursion.