Manual page sections
UNIX manual pages are divided into eight sections or chapters. Each section covers a specific area. Section 9 is a Linux addition.
Section 1: User commands.
Section 2: System calls.
Section 3: Library functions.
Section 4: Device files.
Section 5: File formats.
Section 6: Games.
Section 7: Miscellaneous.
Section 8: System administration.
Section 9: Kernel functions.
Other manual pages.
(The links above are to lists of all manual pages in each section.)