What is data recovery ? And explain about data recovery software?

Data recovery is exactly what it sounds like. Recovering data. This usually is done to media that has been damaged. IE, broken memory stick, clicking hard drive, corrupt hard drive, scratched CD, etc. There is software out there, but it is hard to describe what it is and how it works. The basic idea is to mount the media to ensure that the PCBs aren't damaged, If those don't work then replace the PCBs if possible and try to access the data. If you can mount the volume but not see it then try to trouble shoot accessing the file system. That is the tricky part, especially if you don't know what that is. Then you take an image of the complete drive and virtually mount to retrieve the data.

It isn't a simple procedure of just gettign software to do it.

In what context? Is this a homework question?