A corporation is a company that is legally recognized as a single entity. The corporation itself, and not its owners, is obligated to repay debts and accountable under contracts and legal actions (that is, is a "legal person"). Most commonly, the term corporation is used to refer to a stock corporation (or joint-stock company), which is a corporation where ownership is managed using stock. Non-stock corporations that do not issue stock exist as well, the most common being nonprofit organizations. (A few less common for-profit non-stock corporations also exist.)
In practice, people often use the word company to mean corporation.
Definition Incorporation is the legal process of forming (or incorporating) a new corporation, such as a business or nonprofit. Corporations can be created in any country. In the United States, incorporation is handled by state law, and involves filing articles of incorporation and a variety of other required information with the Secretary of State. (Note that the formation of companies that are not corporations, such as partnerships or LLCs, is not the same as incorporation.)
Definition A C corporation (or C corp) is a type of stock corporation in the United States with certain federal tax treatment. It is the most prevalent kind of corporation.* Most large, well-known American companies are C corporations. C corporations differ from S corporations and other business entities in several ways, including how income is taxed and who may own stock. C corporations have no limit on the number of shareholders allowed to own part of the company. They also allow other corporations, as well as partnerships, trusts, and other businesses, to own stock.
C corps are overwhelmingly popular for early-stage private companies looking to sell part of their business in exchange for investment from individuals and organizations like venture capital firms (which are often partnerships), and for established public companies selling large numbers of stock to individuals and other companies on the public exchange.
In practice, for a few reasons, these companies are usually formed in Delaware, so legalities of all this are defined in Delaware law.** You can think of Delaware law as the primary “language” of U.S. corporate law. Incorporating a company in Delaware has evolved into a national standard for high-growth companies, regardless of where they are physically located.
caution This Guide focuses specifically on C corporations and does not cover how equity compensation works in LLCs, S corporations, partnerships, or sole proprietorships. Both equity and compensation are handled in significantly different ways in each of these kinds of businesses.
Loosely, one way to think about companies is that they are simply a set of contracts, negotiated over time between the people who own and operate the company, and which are enforced by the government, that aligns the interests of everyone involved in creating things customers are willing to pay for. Key to these contracts is a way to precisely track ownership of the company; issuing stock is how companies often choose to do this.