I know what imaginary numbers are, but I'm struggling to understand why the Lorentz transformation makes a time-like dimension space-like. I suppose what I'm really asking is what is the difference between time-like and space-like. I've read that it has something to do with special relativity, but my math skills aren't up to it. Can anyone explain in terms of 'broad concepts'? Or do I just have to accept that, without the math, I'm never going to get a better grasp of the idea?