There is a misconception floating around out there that an S Corp is a standalone entity. Not true. There are several entity types, but the three most common are
Each can elect to be treated as an S Corp for taxation purposes under subchapter S of the revenue code.
So while we might talk about your “S Corp”, we are truly talking about your LLC, partnership or C Corp being treated as an S Corp for taxation. While there are partnerships and C Corps out there who elect to be treated as an S Corp, this book generally focuses on the “S Corp LLC” where the underlying entity is an LLC being taxed as an S corporation. But there are situations where another entity is more appropriate for the S Corp election.
Also, the words member and shareholder are synonymous as well from a conversational perspective- the state considers owners to be members but the IRS considers the owners to be shareholders when issues like distributions, basis, etc. Same is true for equity accounts on the balance sheet.
Taxpayer's Comprehensive Guide to LLCs and S Corps : 2019 Edition