To become a 501(c)(3), an organization must incorporate in the state where its principle office is. This means submitting Articles of Incorporation to the state and paying a fee. Each state provides a form that proscribes what must be included in the Articles – the name of the organization, address, purpose, initial Board of Directors, and the name of the incorporator or incorporators. Pretty simple. The state approves the Articles and sends them back with a stamp that certifies that the organization is a nonprofit corporation in that state.
There is, however, a catch. When it comes time to apply to the IRS for 501(c)(3) status, the Articles of Incorporation are included in the application, and the IRS will reject them if they do not contain certain paragraphs about the charitable nature of the organization and about how the organization will handle dissolution if that event were to ever happen. The organization has to amend its Articles to include those paragraphs and pay a small fee to do so. This takes time, and then the organization has to re-submit the Articles to the IRS, which slows down the process considerably.
Therefore, it is far better if the organization includes the required language about charitable nature and dissolution in the original Articles. The IRS provides that language in its publication 557.