Dictionary.net

The bit in the mode of a Unix filewhich, if set for an executable, tells the kernel to keepthe code loaded in swap space even after it has finishedexecuting on the assumption that it is likely to be used againsoon. This performance optimisation was included in someearly (and recent?) versions of Unix to save reloadingfrequently used programs such as the shell or vi fromdisk.If the sticky bit is set on a directory, an unprivileged usermay not delete or rename files of other users in thatdirectory even if he has write access to the directory.The Unix "ls" command displays a set sticky bit as a "t" inthe permissions of a file or directory.