Before you register as a business, you must determine your legal ownership structure and file with the state.
The most common forms of businesses are:
Sole Proprietorship
Partnerships
Corporations
Limited Liability Companies (LLC)
The answer to the question “What structure makes the most sense?” depends on the individual circumstances of each business owner.
The type of business entity you choose will depend on:
Liability
Taxation
Recordkeeping
For more information from the US Small Business Development Administration, click here.
More information on structures can be found in the Colorado Business Resource Book.
All legal structures are set up at through the Secretary of State once you determined your structure and name and need to be filed with the state.
Articles and information on choosing your business structure from the Small Business Administration.
A comprehensive guide on the different types of business structure and how to choose what is right for your business. From the Colorado Small Business Development Center.
An article that discusses the considerations that should affect your choice of business structure. From FindLaw.
The pros and cons of different business types of ownership, including sole proprietorship, partnering, corporations, and limited liability companies.
Discusses the various types of business structures. Includes links to numerous outside sources. From HG.org Business Resources.
Learn about setting up an LLC in Colorado and associated fees. From Simplify LLC.
LLC or Corporation? by 
The Women's Small Business Start-Up Kit by 
Incorporate Your Business by 
Sole Proprietorship by 