During the design phase, the requirements specification and the systems specification are written. The requirements specification details how the system will work, how data will flow through it and what it will look like to the user. The system specification details the hardware and software that will be needed to run the system. Some things to be done are to design the screen layout, write the error messages, choose the menu buttons, pick the font size, colour and style, how to navigate page to page, what documents are to printed out, the hardware required and how the data dealt will be specified.