Hard Drive Formatting Across Motherboards/CPUs?

Hi all!

I hope to upgrade my motherboard soonish (within a year or so) and want to know how my files would carry over as i do not plan on getting a new hard drive. Would I need to make a backup, could I just plug things in and have it run fine, or something else entirely? Would I need to reinstall windows?

Also, how does formatting work in general, from a technical perspective? How would the awnsers to these questions change if I upgraded my CPU instead? 

Thanks in advance, this is my first build and I'm still a bit new to some of these things.

if you upgrade just the cpu there will be no need to reinstall windows. 

if you upgrade the motherboard you will need to reinstall windows due to the fact the chipset and other hardware on the motherboard has changed.

windows has two different formatting types used, the first one is a quick format which just erases the file directory and the second is the long/normal formatting which will erase across the HDD. 

also if you what to destroy all the data on a HDD you can use a program called Dban which writes zeros and ones across the HDD to ensure that all data is wiped out.