The book 'SQL Server 2012 Query Performance Tuning' focuses on optimizing SQL queries for the SQL Server 2012 database management system. It covers a wide range of optimization strategies and techniques from basic concepts to advanced skills. Topics include SQL Server 2012 overview, importance of query performance optimization, index optimization, query execution plans, statistics, query optimizer, stored procedures and parameterized queries, resource management, temporary objects and table variables, and performance monitoring tools like SQL Server Profiler and DMVs.