Winding up a company is the process of ending its existence, involving the dissolution of its affairs, collection of assets, and payment of debts. The Companies Act, 1956 outlines three modes of winding up: compulsory winding by the tribunal, members' voluntary winding up, and creditors' voluntary winding up, each necessitating the appointment of a liquidator to manage the process. Grounds for compulsory winding include inability to pay debts and just and equitable reasons, while voluntary winding includes procedures dependent on the type of voluntary winding chosen.