Solid-state drive
The solid state drive technology is improving quickly, and new SSD models are being introduced often. However, they have not gained popularity among many users. We still find that HDDs are still dominating the market. Sales of SSDs are expected to escalate and overturn that of HDDs after 2020. The biggest draw back to SSDs over hard disk drives is that SSDs have a limited amount of read and writes it can take before the sector fails, as is not a issue with traditional hard disk drives.  This is not a problem for most people, unless if you are heavily reading and writing to the SSD. However, modern SSDs often have more read and write cycles, and there are specific SSDs that can sustain such heavy read and writes. They are often used in servers.