Man pages are organizeed into sections. There are 9 sections of Linux man pages.
Section # 1 : User command, it contains executable programs and shell commands
Section # 2 : System calls, all the functions provided by the kernel
Section # 3 : Library calls, functions within program libraries
Section # 4 : Special files (usually found in /dev)
Section # 5 : File formats and conventions, eg /etc/passwd
Section # 6 : Games
Section # 7 : Miscellaneous, including macro packages and conventions
Section # 8 : System administration command
Section # 9 : Kernel routines, which is not standard for other sections