What is the "back up" thing on a laptop?

Hi, I have just got a new laptop and my friend was telling me to "do the back up first".

What is the "back up" option? what does it do? Will it keep the main files of the computer, aside in the hard disk so if I reset my computer (install the windows again) then I could put these files back in and use the laptop from then just like if it was brand new? or will formatting the hard disk delete these files as well after doing the back up? please help me hereWhat is the "back up" thing on a laptop?
What a system back up does is it stores and configures a statis file of your computer. Your features, settings, and system recovery options at that frame of time so that if your computer goes bad or something happens then the "back up" file, can rewrite these back to a time when your computer was known at a GOOD configuration. This does not affect files in the same way, files will remain even if you roll your settings back to a recent setting. Resetting the hard drive will erase the backup files and render them useless, backing up on seperate storage drives is possible but not from the same harddrvive.What is the "back up" thing on a laptop?
It means saving important files, so that you can restore in case your computer dies or something bad happens. Always "back up" important files, so that you can access them again, whenever needed.