HandBrake is a free tool which comes with plenty of features for beginners and intermediate users alike. This free cross platform, open source program can *convert a DVD into formats such as MP4, MKV, AVI or OGM that can be played on your PC, Mac, Linux box, iPod, PSP, Apple TV, Television, iPhone, or mobile phone. Just follow this guide.

Step1. Download and install Handbrake

To get started you'll have to install the software. At the time of writing the software was up to version 0.9 and available free at the HandBrake Web site. Once installed open the HandBrake application. The application should default to a simple interface like the screenshot below.
 

 

Step 2, Insert DVD movie

Once you've selected the DVD you want to copy or back up insert it into your Mac. Now click on the icon that says "Source" and click your DVD drive.

Click Open and you will be able to see many titles included in this DVD disk. Choose the longest title if this is a movie DVD, or choose your favorite chapter if this is an episode.

Step 3, Set the output format

In this example I've selected MKV files as output format but the principle is the same for other formats. Once the format is selected you can select other settings such as video quality, audio track, Audio Sample Rate, bitrate, Picture Settings, etc.

Step 4, Rip DVD

Check all settings and click Start. A progress bar will show its ripping speed; depends on many factors like machine speed  filesize, etc.