Node analysis requires a ground node to establish a reference point for potential, typically set to zero, which simplifies calculations. The potential of each node is defined relative to this reference, allowing for the formulation of equations based on node voltages. While it is common to assign a ground node, it is not strictly necessary, as any node can serve as a reference point. The choice of ground node, such as setting U1 to zero, is a matter of convenience and does not affect the overall analysis. Ultimately, understanding the role of the ground node is crucial for accurate node potential calculations.