Mic placement: On-axis or Off-axis

[TheBones]

I hear the terms On/Off axis quite a bit and i have done alot of experimenting with mic placement myself however i was wondering if anyone new of any resource online that might be able to spell it out via a diagram or explain it more than just place the microphone off-axis from the speaker cone. might be a reallllly dumb question just wondering.

 

[grimtraveller]

Well, off axis simply means "not dead on centre" or not pointing directly at the cone. How will a diagram help ? Imagination will get us further than a drawing sometimes.
I hope that doesn't come across as rude.