Essentially, because SSDs have no moving parts and use flash memory, they can read and write data much faster than an HDD can with its spinning platters and reading head. Just in case you're not familiar, it helps to know the differences between an SSD and HDD. In that case, what's the best way to use an SSD and HDD combo? We'll show you how to use an SSD and HDD together for best results. However, since SSDs are more expensive, you might not be able to afford a large enough SSD to store all your data on. You probably know that a solid-state drive (SSD) is a huge upgrade for your computer because it runs much faster than a mechanical hard disk drive (HDD).