Dual booting
 

Hi guys. I'm in a bit of a confusion.
Disk partitioning rules say that there can be only one active partition at a time. But then how the hell does dual booting work at all??

Active partition means, all other operating systems will be controlled by the active partition. If you take an example of dual booting of Linux and Windwos, Linux will be installed in active partition and all other operating systems will be controlled by Linux boot loader.