Is it LILO or lilo? I thought everything was lower case...
When your computer begins booting, you (should) see LILO on the screen. This is not a named program, in the way that all your other programs have names. It is bootstrap code at the very beginning of your disk, which has the special purpose of starting your computer system. I call it LILO (upper case), because it calls itself LILO, and I think the rest of the world may also call it that.
Now, the boot installer program, which you run beforehand to set up the bootstrap; that is actually a Linux program, usually found in /sbin/lilo. A big part of solving the riddles of LILO is to remember that the these are two very different pieces of code. Pay close attention when I say lilo or LILO; most of the time it is important which one I'm talking about!