It's a language and database system that most web sites use. (forums use it to store users, posts etc and then retreive them to display threads etc)
Should totally sim on the very first day on the new server IMO. "30-day money back guarantee. You have nothing to lose!" in case it just dies then. >_>
My SQL post was in response to Fungus's question about my ISP space. The new server has SQL. Without it, vBulletin forums can't work.
We're back. Those 5 hours of lost time devastated me. On a serious note Kudos to Cribb + Flack + All concerned for getting us back + running well & effectively so quickly, and sorting out the situation. Great to be back.