I have been playing Chrono Trigger and I noticed that at the end of most or all battles, I get "Tech Points" along with experience, money, and items. I have not yet seen what effect these Tech Points have. So, what do they do?
"Tech Points" are similar to experience, but they help to unlock more of the techs (and/or spells) each character has access to. Unlike in other games, you don't learn techs based on your level.
In the "Tech" menu, you'll see a list of the techs each character can learn, and you can see how many more TP it will take to learn the next one on the list. Confusingly, these are referred to as "Skill Points" in the tech menu.