To 'clone' a disk is to make an exact 'twin' of it. So, if that disk is bootable, the 'twin' will be also. So, if that is your internal hard drive, it will boot from the 'clone', too. This means that if you have an accident or Windows problem, you can go get your clone, clone back to your damaged drive, and be back in operation quickly.
There are , biggest con being it takes a good 20 minutes for 70 GB, and over an hour for 1 GB. Also, the drive TARGET receiving the SOURCE, has to be bigger than the source.
There are a number of cloners 'out there', but most folks I've run into like . I also like (use Windows Method B there in the link, to make it). Macrium will let you use a smaller disk target than the source, so long as the target is bigger than the total used space on the source. So try that one first. Macrium only works within Windows, and on external hardrives, not sticks; Clonezilla only works as a standalone program (booted outside of Windows), but will clone Windows or Linux internal or external drives, sticks, etc. Takes a long time to clone one stick to another, but worth it.
, and depend on who made the backup. This is a problem, for if you have an old backup but the company went out of business or you don't remember who you used to make the backup, you can't restore it. Further, often a backup cannot be restored if you're not also in Windows at the time. So plan on learning to Clone.