the engineer gets a problem she has to solve, in the best case as a complete specification. the engineer solves this problem with the means he has learnt, starts with a decomposition, applies standard solutions when possible, invents new solutions when necessary. when finding new solutions the engineer uses in most cases "incremental design", meaning that starting from an existing solution by modifications a new product is made. Less often, an engineer has to apply "radical design" which means inventing something new with no similar thing to build upon (e.g. the first space ships). the engineer tries to finish a prototype early enough to have time for testing, and, if necessary, improvements for the final product.