What is initrd?

I didn’t know what the purpose of the initrd file was. I had some vague idea that it had something to do with the ramdisk.

Varun was looking at this Debian Wiki page and was trying to get a preseeded Debian Installer ISO. While hacking the initrd, we noticed that the initrd looked like a proper / filesystem – with a /bin, /etc et al. It is then that I learnt that initrd is like an “image” of the ramdisk to be used by the Linux kernel.