Architectural drawings and models have one major function in common and that is communication. They are the means by which architects communicate with other people such as prospective clients and the public, or give detailed instructions to a builder. They also enable architects to develop their ideas. The analysis of a series of drawings of a building can reveal how an architect’s ideas changed during the evolution of the design or during the course of the construction. They can also indicate the architect’s approach to design and reveal their intentions at a particular moment. Architectural drawings and models are made for a variety of purposes and these determine the nature and quality of the information included. A small-scale drawing with few details may be sufficient to convince a client of the merits of a project. Finished architectural drawings to be used by a contractor on site are called working drawings and they form a legal contract between the owner and contractor. Sometimes individual drawings and models are made of particular features, such as decorative mouldings. These may be full-sized to enable craftspeople to carve the detail accurately.