The articles of incorporation (referred to in Delaware as the "certificate of incorportion") is the corporation's charter document. This is the document that is filed with the state to incorporate the corporate entity and continues to serve as the corporation's foundational corporate governance document.
The articles of incorporation may be very simple, including only the minimum statutory requirements (such as those listed in Section 102(a) if the Delaware General Corporation Law). These minimum requirements would typically include (1) the names of the corporation, (2) the address of the registered office and the name of the registered agent, (3) the number of authorized shares, and (4) the name and address of the incorporators. Some statutes require additional information, such as (5) a statement of corporate purpose, and (5) a statement of the corporation's duration, or (6) names and addresses of initial directors.
The articles of incorporation can be much more complex than the simple outline above, however, spanning dozens of pages. This is particularly the case when the corporation has multiple series of preferred stock authorized, the terms of which will be deemed to be a part of the articles of incorporation.
The articles of incorporation can be amended at any time after their filing. Amending the articles of incorporation requires a shareholder vote, typically a majority of the outstanding shares.