In the last decade, deep learning and word embeddings have made significant impacts on information retrieval (IR) by adding techniques based in neural networks and language models. At the same time, certain search modalities such as neural IR and conversational search have become more popular. This book, written by international academic and industry experts, brings the field up to date with detailed discussions of these new approaches and techniques. The book is organized in three sections: Foundations, Adaptations and Concerns, and Verticals.

Under Foundations, we address topics that form the basic structure of any modern IR system, including recommender systems. These new techniques are developed to augment indexing, retrieval, and ranking. Neural IR, recommender systems, evaluation, query-driven functionality, and knowledge graphs are covered in this section.

IR systems need to adapt to specific user characteristics and preferences, and techniques that were considered too niche a few years ago are now a matter of system design consideration. The Adaptations and Concerns section covers the following topics: conversational search, cross-language retrieval, temporal extraction and retrieval, bias in retrieval systems, and privacy in search.

While web search engines are the most popular information access point, there are cases where specific verticals provide a better experience in terms of content and relevance. The Verticals section describes eCommerce, professional search, personal collections, music retrieval, and biomedicine as examples.

Omar Alonso is a part-time lecturer at the Khoury College of Computer Sciences at Northeastern University. He earned his doctorate in computer science from the University of California, Davis. His main research areas include information retrieval, search quality evaluation, and knowledge graphs. He teaches the course CS 6200: Information Retrieval. Another area of research for Alonso is label quality and the practice of designing and implementing hybrid human-machine systems, topics that he covered in his book, “The Practice of Crowdsourcing.”
Currently, Alonso is a senior manager of applied science at Amazon. In the past, he was a principal data scientist lead at Microsoft in San Jose, where he worked on the intersection of social media, temporal information, knowledge graphs, and human computation. He is the co-organizer of DESIRES, a new information retrieval conference with a focus on system implementation and experimental design. Additionally, Alonso was co-chair of the crowdsourcing and human computation track for WWW 2019 and WWW 2021.

Ricardo Baeza-Yates is a visiting full professor and the director of research at Northeastern University's Institute for Experiential Artificial Intelligence with a courtesy appointment in the Khoury College of Computer Sciences, based in Silicon Valley.
Baeza-Yates came to Northeastern after serving as chief technology officer of NTENT, a semantic search technology company based in California. Prior to these roles, he was vice president of research at Yahoo Labs in Sunnyvale, California from August 2014 to February 2016. Before joining Yahoo Labs in California, he founded or led Yahoo Labs in Barcelona, Spain; Santiago, Chile; Haifa, Israel; and London.
Baeza-Yates is a part-time professor at the Universitat Pompeu Fabra in Barcelona, Spain and the Universidad de Chile in Santiago. Until 2004, he was a professor and founding director of the Center for Web Research at the Universidad de Chile.
Baeza-Yates is a co-author of the best-seller Modern Information Retrieval textbook (Addison-Wesley, 1999), whose 2011 expanded edition won the ASIST Book of the Year award. He is also a co-author of the second edition of the Handbook of Algorithms and Data Structures (Addison-Wesley, 1991) and co-editor of Information Retrieval: Algorithms and Data Structures (Prentice-Hall, 1992), among more than 600 other publications.
Baeza-Yates served on the board of governors of the IEEE Computer Society from 2002 to 2004, and on the ACM Council from 2012 to 2016. He has received the Organization of American States award for young researchers in exact sciences, the Graham Medal for innovation in computing from the University of Waterloo, the CLEI Latin American distinction for contributions to computing in the region, and the National Award of the Chilean Association of Engineers, among other distinctions. In 2003, Baeza-Yates became the first computer scientist to be elected to the Chilean Academy of Sciences and, since 2010, he has been a founding member of the Chilean Academy of Engineering. He is a fellow of the ACM and the IEEE.