The goal is to introduce the theoretical foundations and algorithmic-engineering tools for the design, analysis and implementation f IR systems. We will study several algorithmic techniques which are nowadays deployed to design IR applications, like: algorithms for data streaming, data compression, data indexing, data sketching and data searching. This algorithmic machinery will be used to study the design and analysis of the main components of a modern search engine, and to investigate their computational limitations. Together with the theoretical study of the previous, the course will consist also of a practical activity (3 CFU) in which the students will pratice with the open-source tools nowadays available for the implementation of a search engine and of other IR applications.