如何控制Emacs如何制作备份文件？

Emacs puts backup files named foo~ everywhere and I don't like having to remember to delete them. Also, if I edit a file that has a hard link somewhere else in the file system, the hard link points to the backup when I'm done editing, and that's confusing and awful. How can I either eliminate these backup files, or have them go somewhere other than the same directory? everywhere a