What does disk initialization do?

I've lost the drives on one of my HD's ;-(

I've manage to recreate the file tables (or whatever it's called in NTFS),
and now I can access the files/logical, basic drives from the WinXP command
console :-)

But I still can't access them from WinXP, and the disk manager says that the
disk has to be initialized so that the "logical disk manager" can access the
HD :-/

This is done with a few mouse clicks, I know, but I don't want to initialize
the HD in WinXP before I'm sure that my data won't disappear.

I can't find any exact descriptions of the impact of the disk initialization
process anywhere on Microsoft.com.

Can you tell me what disk initialization do?

(not what it's for, I know that very well)