What element does a rectangle represent in a data flow diagram?

In a data flow diagram, a rectangle is used to represent data processing. This symbol indicates that there is some form of transformation or manipulation occurring with the data flowing through the system. The rectangle signifies a process that takes input data, processes it in some way (like calculations, validations, or converting formats), and produces output data.

Understanding this concept is vital because data flow diagrams are integral to modeling systems in software design. They visually depict how data moves through various components of the system and help identify where processing occurs, allowing developers to ensure that data is handled securely and efficiently throughout an application. The correct representation of elements within these diagrams aids in clear communication among stakeholders involved in system design and analysis.