Architects begin from the ground up. The architects work with what they find on the site. The phrase comes from architecture, where it is used to describe a project that has never been built before. The word "green" in this context means virgin or unoccupied. Thus, a greenfield project is a new opportunity for improvement or advancement. These projects are attractive because there are no limitations imposed by existing structures, utility connections, or other factors such as zoning that may limit what can be done with the land. For example, an architect could design and draw up plans for a new house on a blank slate. Or an architect might adapt old buildings or even complete designs himself to start his own business. Greenfield projects offer more freedom than most other types of projects. They are usually associated with land that has not yet been developed any other way; therefore, it is possible to make major changes without worrying about whether they will have an impact on future requirements. The phrase "blue field" or "brown field" project refers to a similar type of project that uses material from another structure instead of starting from scratch. For example, an architect might reuse parts of an existing building in a new design.