To convert DVD movies to play on Plex, Android or Iphone devices.
I only use these tools to rip DVD for my personal use, some DVDs are copyrighted in a way that ripping them is illegal even for personal use.
Update - New Way use MakeMKV instead of DVDDecrypter:
I now use MakeMKV to extract files from DVDs or Blu-Ray, then I use the current version of Handbrake to compress to .mp4 files.
Insert your DVD and click on the DVD drive image
It will scan the drive to find titles
Select the movie, usually the first large file, update the output folder and click MakeMKV button.
Then continue with Handbrake as below.