I will admit that I am ignorant, so educate me. What is trail? What part of the front end trails and what leads?

If I I look at two bikes, one with a fork that is almost straight and a second with the old school curve, which one is low trail?
A straight fork to my mind will be twitchy, and a long curved one "slower" steering.
Straight forks can have a lot or a little offset. It's the offset that matters, not how the tip of the fork gets there.