Here, unless you decide to go work for the Dept of Corrections (prisons) or something (which are run by the state) you are hired by a District, which is funded by state, federal and local sources. After a probationary period (usually 2 years) a teacher is either non-reelected or given tenure, and what tenure means is that you can't be fired willy-nilly -- you have to go through a pretty extensive process and, theoretically, the union fights on your behalf. Once you're tenured (which I am) you have to do something pretty bad to get fired, other than just being a bad teacher. But if the district simply doesn't have enough money to pay you the following year, or thinks they won't, they're allowed to lay you off, but any open positions have to be filled by laid-off teachers in order of seniority.

I'm sure that's clear as mud :)