Lens Acronyms

[Sideburns]

You had it backwards but the others already covered that. For maximum depth of field you'll want to set the aperture to f/8 or f/11. Most DSLRs are diffraction limited at about that setting, so stopping down beyond that (f/22 for example) will result in soft photos. It's like squinting to see a distant object, but if you squint too much everything gets blurry. The only reason you'd want to stop the lens all the way down like this is if you're specifically trying to get some sort of motion or blurred action photo and need a slower shutter speed. These photos aren't going to be sharp anyways due to the blur effect, so then it can be appropriate. An example might be a waterfall shot during the day when you want a nice smooth flow of water. Even better would be a 4-stop neutral density (ND) filter. That'll let you slow down daylight photos enough to get a nice flowing look for water shots while still letting you shoot at a more reasonable aperture like f/8 or f/11 which will leave everything else in the photo at maximum sharpness.

I'm not sure what you're talking about, but there isn't really any noticeable "blur" when shooting at f22 or smaller. It especially depends on your lens, as well.

F22 is probably one of the most popular apertures to be used...