<human>:  What are the primary differences between a C corporation and an S corporation?
<bot>: The primary difference between a C corporation and an S corporation is that a C corporation is subject to double taxation, while an S corporation is generally only subject to one level of taxation. Another difference is that C corporations have an unlimited number of shareholders, while an S corporation is limited to fewer than 100 shareholders. Finally, C corporations generally have more formal record keeping and reporting requirements than an S corporation.