The book examines in detail the main subsystems and functions of the Linux 2.6 series kernels, including design features, implementation and corresponding software interfaces. Topics covered include: process scheduling, kernel time management and timers, system call interfaces, addressing and memory management considerations, page cache, VFS, synchronization mechanisms, portability issues, and debugging considerations. The author of the book is a developer of the main subsystems of the Linux kernel. The kernel is considered from both theoretical and applied points of view, which can attract readers with different interests and needs. The book can be recommended to both beginners and experienced software developers, and also as additional educational materials.