Whats the best software or program can I use for DVD copying?

I tried to use my computer to copy one of my dvd's but the protection and licensing encoded on the dvd wont allow to. Im sure thats to prevent some kind of illegal action. But i heard that I needed a dvd copying software to do it. So whats the BEST one to use? Im not doing anything illegal, Im just making another copy, ya know, like a back up.