Map Reduce is the distributed, parallel computing programming model for Hadoop. Inspired from Google Map Reduce research paper. Hadoop includes implementation of Map Reduce programming model. In Map Reduce there are two phases, not surprisingly Map and Reduce. To be precise in between Map and Reduce phase, there is another phase called sort and shuffle. Job Tracker in Name Node machine manages other cluster nodes. Map Reduce programming can be written in Java. If you like SQL or other non- Java languages, you are still in luck. You can use utility called Hadoop Streaming.