This document discusses the pros and cons of using open source software in libraries. It begins by defining open source software and licenses. It then outlines several areas where open source software can be applied in libraries, such as for integrated library management systems, content management systems, and digital libraries. The pros of open source software include lower costs, easier licensing, better quality control, and the ability to modify the software. However, the cons include a lack of personal support, need for training, and responsibility issues. The document concludes that open source software is suitable for long-term library use if its advantages and disadvantages are carefully considered.