One of the best reasons for incorporating, or forming a limited liability company, is to separate your personal assets from your company's assets. If you conduct business without using a corporation, or limited liability company, you place your assets at risk. Separating your personal property from your business property, and using a legal form such as a corporation, can help protect your personal property. Incorporation or formation of a limited liability company also allows you to take advantage of the statutory and judicial laws of Delaware, to help you plan how your business runs. An example: Delaware Law allows for a version of the Limited Liability Company often called a Serial LLC. An LLC is normally very simple to create.
The major difference between an LLC and a sole proprietorship or a partnership is the limitation of liability an LLC brings to you. But say that you wanted to conduct more than one type of business, and you didn't want to create a separate corporation or limited liability company for each. The "Serial" LLC allows different lines of business to be treated separately from each other from a liability standpoint. So, for example, an LLC that owns several apartment buildings may insulate the LLC from liability for each individual building, if the operating agreement allows for it, and the operating agreement is followed. For more information take a look at the Limited Liability Company Act of the Delaware Code (especially, Title 6, Section 18-215; Series of members, managers or limited liability company interests).