System Restore is an old (goes back to Windows Me) and outmoded technology that was superseded long ago by modern backup software. Today, System Restore has no real use and is disabled in a default install of Windows.
Even though it's called System Restore, it cannot, in fact, restore your computer nor can it send your computer back in time. Only a backup can do these things. A restore point is a copy of the essential underpinnings of Windows - registry hives, system folders and system drivers. The original goal of System Restore was to (hopefully) restore the basic guts of Windows, to give users an opportunity to try to work their way out of a problem.
When System Restore was created, backing up and restoring the C: drive was a difficult and highly technical job beyond the reach of the average user. System Restore was intended to give everyday users a chance to repair their computers in the absence of user-friendly backup technology.
Today, the backup industry produces plenty of excellent quality, convenient and user friendly backup software that makes it quick and easy to backup and restore a computer in literally minutes. Now there's no longer a need for System Restore. Moreover, the ability to conveniently backup and restore overcomes System Restore's most serious problem: When you restore a restore point, your computer becomes a mixture of old and new system components. If Windows has changed significantly from the time a restore point was made, adding back old system components can cause crashes. This is why restore points age out and are automatically deleted after a set amount of time, and it also explains why all existing restore points are deleted after a Windows feature upgrade is installed.
BTW: Modern backup applications have also made another old-time Windows utility redundant - the restore disk. Why try to troubleshoot, repair or reinstall Windows when you can easily send it back in time to when everything was great?