Section 2(62) of Companies Act defines a one-person company as a company that has only one person as to its member. Furthermore, members of a company are nothing but subscribers to its memorandum of association, or its shareholders. So, an OPC is effectively a company that has only one shareholder as its member.
Such companies are generally created when there is only one founder/promoter for the business. Entrepreneurs whose businesses lie in early stages prefer to create OPCs instead of sole proprietorship business because of the several advantages that OPCs offer.