Open Odin and the Options tab looks like a row of checkboxes nobody dares to touch. Most guides say "leave everything at default" and move on, which is fine until something goes wrong and you need to know what the checkbox you just ticked actually did. Here's what the important ones do, in plain terms.

Auto Reboot. The default. After the flash completes, Odin tells the phone to reboot into the freshly written system. You want this on for a normal flash. The only time people turn it off is when they're chaining operations — for example, flashing firmware and then immediately booting into recovery to wipe cache — because an automatic reboot would skip the window where you can catch the recovery key combo. For a standard flash, leave it on.

F. Reset Time. Also on by default, and also something to leave alone. It resets Odin's internal flash timer between operations. It has no effect on your phone and doesn't change what gets written.…