How can you hide information inside a jpg or gif photo?

Question

How can I write some information inside a photo file like jpg or gif without destroying the image? and of course without showing it on the photo since the whole idea is to s

Answer 1

In windows you can use simple command to hide archive in image : copy /b cat.jpg + Documents.rar cat_new.jpg. And then use for example winrar to extract data ftom image as from archive.
But better way is to use Steganography.
simple program for it for linux and windows : http://linux01.gwdg.de/~alatham/stego.html
using this program you will use pass phrase, without it nobody even will know, that you hided some data in picture ))