Search Engines: Information Retrieval in Practice 搜索引擎：信息检索实践， W. Bruce Croft is a Distinguished Professor in the Department of Computer Science at the University of Massachusetts, Amherst, which he joined in 1979. In 1992, he became the Director of the Center for Intelligent Information Retrieval (CIIR), which combines basic research with technology transfer to a variety of government and industry partners. He has published more than 180 articles related to information retrieval. Dr. Croft was elected a Fellow of ACM in 1997, received the Research Award from the American Society for Information Science and Technology in 2000, and received the Gerard Salton Award from the ACM Special Interest Group in Information Retrieval (SIGIR) in 2003. Donald Metzler is a Research Scientist in the Search and Computational Advertising group at Yahoo! Research in Santa Clara, CA. He obtained his Ph.D. from the University of Massachusetts in 2007. During his graduate studies he was awarded a Microsoft Live Labs Graduate Fellowship. His research interests include formal information retrieval models, web search, advertising, and machine learning. Trevor Strohman is a software engineer in the Google search quality division. His Ph.D., from the University of Massachusetts Amherst, focused on high-performance text retrieval systems that are easily adaptable to fit specific retrieval applications. He has published papers and presented a tutorial at the top information retrieval conference, SIGIR. He is the creator of the Galago search engine, and the primary developer of the Indri search engine (www.lemurproject.org/indri). He has ten years of professional software development experience, including desktop, server, and web applications.