Donald Metzler is a Staff Software Engineer at Google. Prior to that he was a Senior Research Scientist at Yahoo! and a Research Assistant Professor of Computer Science at the University of Southern California (USC). He is an active member of the information retrieval, Web search, and natural language processing research communities. He has published over 40 research papers, has 4 patents granted, and is a co-author of "Search Engines: Information Retrieval in Practice".