I have tried searching the web, however all they do was explain how to do a render to texture, can anyone explain what exactly is this technique and how is it use for?

Let's say you're in a car and you want to do a rear-view mirror. Create another camera and render its output to a texture and put that texture on the mirror.

Let's say you want to watch a movie inside your application. Render that movie on a texture and put it on a side of a block as a texture and bam you've got a movie playing in your game.

Let's say you want to make instruments inside your cockpit (may be a plane or a car or whatever), do whatever you need to do to update the image that it should be displaying (numbers of channels, frequencies, gps data, maps) and render that to a texture and put that texture on some sort of panel.

I am sure you can figure out a lot more examples now.

Thanks for the replies i finally understood the purpose of this technique