New to Arduino : What is the Programmer Menu in IDE for?

Hi, I'm new to Arduino. I have 2 Leonardos. i want to start working with them, btw i was exploring the IDE last two days, I Saw a sub menu in tools named programmer. what this menu is for? does this have anything to do with arduino leonardo? which one should be the default one if i'm just using my leonardo straight to my computer?

"programmer" is used by the "burn bootloader" and "upload using programmer" options. It's value is not important for the normal ("upload" (using bootloader)) sketch loading.