A solid-state drive (SSD) is a media that uses flash modules to store data. The solid-state drives remain relatively new and more pricey than the classic hard disk drives (HDD), however they are considerably faster, so they are often employed for Operating Systems and apps on both PCs and servers. An SSD is recommended because it doesn't have spinning disks that limit its speed and could cause overheating like it could happen with an HDD. Lots of companies use SSDs for caching purposes, so all of the site content which is accessed more often will be kept on this kind of drives, while all other content will be held on regular HDDs. The reason to use such a setup is to balance the price and overall performance of their Internet hosting platform and to lower the load on the HDDs caused by numerous reading and writing processes.