Quick question

I'm learning PHP to create some cool web mashup site. Everything is going great so far; I've got most of the database design down.

Anyway, just one question: what is abstraction? I keep hearing this phrase get banded around a lot and when I asked my professor about he gave me a funny look like he didn't know what I was on about. You guys at /pr/ seem a lot smarter than him, can you help me out?

THANKS IN ADVANCE

what is the CPU architecture of the server
It's running on a WRT54G; so 200Mhz MIPS processor. I figure I can get it to scale better buy clustering a few of them (plus they only cost like $50 each).