A huge amount of information is collected and dynamically updated every second around the world. Graph algorithms, which are based on mathematics specifically designed to study the relationships between data, help to understand these gigantic volumes. And, crucially these days, they improve contextual information for artificial intelligence. This book is a practical guide to getting started with graph algorithms. At the beginning of the description of each category of algorithms, a table is provided that will help you quickly select the desired algorithm and familiarize yourself with examples of its use. The publication is intended for developers and data scientists. The experience of using Apache Spark ™ or Neo4j platforms is desirable for studying the material of the book, but it is also useful for studying more general concepts of graph theory, regardless of the choice of graph technologies.