How does the red hair gene work?

One giorno I was thinking about what my future kids would look like ( if I have any in the future) and then I thought about if any of them would have red hair. My grandpa, aunt, and a few cousins have red hair, so I looked it up on Google and got multiple risposte for the red hair gene. Some detto that both parents have to have red hair somewhere in there family, and then i got risposte that say it skipped generations, but i don't know which one is right o are both right? Could someone explain how that works?