Techniques for eliciting requirements. Languages and models for representing requirements. Analysis and validation techniques, including need, goal and use-case analysis. Requirements in the context of system engineering. Specifying and measuring external qualities: performance, reliability, availability, safety, security, etc. Specifying and analyzing requirements for various types of systems: embedded systems, consumer systems, web-based systems, business systems, systems for scientists and other engineers. Resolving feature interactions. Requirements documentation standards. Traceability. Human factors. Requirements in the context agile processes. Requirements management: Handling requirements changes.