The Linux sticky bit for directories, it prevents unprivileged users from removing or renaming a file in the directory unless they own the file or the directory. This is called the restricted deletion flag for the directory.
The directories /tmp and /var/tmp are typical candidates for the linux sticky bit - they are directories in which any user can typically create files. The permissions for these two directories are often read, write, and execute for everyone (user, group, and other). But users should not be able to delete or rename files owned by others.