3.0 Introduction A product line is a set of products sharing a common, managed set of features that satisfy the specific needs of a particular market segment or mission. Product lines promise to become the dominating production software paradigm of the new century. Product flexibility is the new anthem of the marketplace, and product lines fulfill the promise of tailor-made systems built specifically for the needs of particular customers or customer groups.
Product lines are, of course, nothing new in manufacturing.
Each of these exploits commonality in different ways. But software product lines based on inter-product commonality are a relatively new concept and are rapidly emerging as a viable and important software development paradigm. Companies are finding that the practice of building sets of related systems from common assets can yield remarkable quantitative improvements in productivity, time to market, product quality, and customer satisfaction. Organizations that acquire, as opposed to build, software systems are finding that commissioning a set of related systems as a commonly-developed product line yields economies in delivery time, cost, simplified training, and streamlined acquisition. We believe that product lines will be the predominant software paradigm at the beginning of the new century.