Wikipedia defines a "Kernel" as:
which I don't think is a very good definition. A kernel in my mind is something which manages the computers resources (memory, disk, processor time etc) and abstracts the hardware.
The marketing division of the Sirius Cybernetics Corporation defines a Kernel as
Your plastic pal that's fun to be with.
Anyone got anything that they think they should add to this definition?
The kernel can have bits loaded at run time; each bit is called a Kernel Module.
Linux is an example of a MonolithicKernel, while TheHurd is an example of a MicroKernel
Remember, you can't boot a kernel by itself, hence the ReligiousWar of RMS vs common usage. Attempting to boot "Linux" would result in something along the lines of "Kernel Panic: Cannot find init". Trying to boot what RMS calls GNU/Linux would result in the OS we know and love.
97 pages link to Kernel: