The phrase “sticky bit” when talking about a file can mean one two things; on older UNIX systems it meant that the file should not be swapped out of RAM. On modern systems (such as Linux) it refers to the “chmod u+s” syntax, which tells the system that, although the file has been run by (say, a normal user called “steve”), because it is (a) owned by (typically) root and has the sticky bit set (-rwxr-sr-x), then it will actually be executed with root permissions. This is one reason why you can’t “donate” your files to another user: “steve$ chown root myfile” because it could be used to escalate your privileges. With this mechanism, root must explicitly set the sticky bit on specific (trusted) binaries. The sticky bit can’t be set on shell scripts.