Traditional approaches to software reuse have proved ineffective in addressing the software crisis in practice. Over the past few years a new approach to software reuse has gained considerable attention both by industry and academia. This approach is known as software product line development and it supports large-grained intra-organization software reuse. Product lines have been used by the manufacturing industry for a long time to reduce costs and increase productivity by exploiting commonalties between products. However, product line practice in the software industry is a relatively new concept. Studies have shown that organizations can yield remarkable improvements in productivity, time to market, product quality and customer satisfaction by applying this approach. This paper presents some of the basic concepts of product line development and summarizes some of the possible benefits, risks and costs associated with this approach to software reuse.