Writing a Requirements Document For Multimedia and Software Projects

Requirements include descriptions of system properties, specifications for how the system should work, and constraints placed upon the development process. Generally, requirements are statements of what a system should do rather than how it should do it. The answers to how questions fall into the realm of design. Requirements specifications should not include design solutions (except for interface requirements, which often include embedded design).
Requirements come from end users, from customers, and sometimes from developers. End users tend to state requirements in descriptive or narrative terms ("I'd like a welcome screen with links to the things I use regularly, and I want to be able to select from a couple of different color schemes for the welcome screen") which might need to be broken down into individual requirement statements. Customers, who may well be different from end users, are the people who are paying for the development of the system. Their requirements will often be stated in terms of costs or scheduling issues. Developers might have requirements related to system performance and other technical topics.
It's important to have all these groups contribute to the requirements document to create a fuller description of the system. The practice of including these groups also helps to ensure that everyone is in agreement about what is to be done before development begins.