Building software systems with reusable components brings many advantages. The development becomes more efficient, the reliability of the products is enhanced, and the maintenance requirement is significantly reduced. Designing, developing and maintaining components for reuse is, however, a very complex process which places high requirements not only for the component functionality and flexibility, but also for the development organization. In this paper we discuss the different levels of component reuse, and certain aspects of component development, such as component generality and efficiency, compatibility problems, the demands on development environment, maintenance, etc. The evolution of requirements for products generates new requirements for components, if components are not enough general and mature. This dynamism determines the component life cycle where the component first reaches its stability and later degenerates in an asset that is difficult to use, difficult to adapt and...