Sticky text and append-only directories
A special file mode, called the sticky bit (mode S_ISVTX), is used to indicate special treatment for directories.
It is ignored for regular files. See chmod for an explanation of file modes.
A directory whose `sticky bit' is set becomes an append-only directory, or, more accurately, a directory in which the deletion of files is restricted.
A file in a sticky directory may only be removed or renamed by a user if the user has write permission for the directory and the user is the owner of the file, the owner of the directory, or the super-user.
This feature is usefully applied to directories such as /tmp which must be publicly writable but should deny users the license to arbitrarily delete or rename each others' files. Any user may create a sticky directory.
See chmod for details about modifying file modes.
“You may not control all the events that happen to you, but you can decide not to be reduced by them” ~ Maya Angelou
chmod - Change access permissions