Fusion Drive

The Fusion Drive is Apple's propietary implementation of a solid-state hybrid drive (SSHD), combining the speed benefits of an solid-state drive (SSD) with the more cost-effective storage space of a conventional hard drive. It was first introduced in 2012 as an option for the Intel-based iMac.

History
Fusion Drives were also offered as an option for the Mac mini from 2012 to 2018. This option was discontinued from the 27-inch iMac with Retina display in 2020. With the dropping prices of storage devices, SSDs have become a more appealing option.

Splitting
It is possible to split the solid-state drive and hard drive components of a Fusion Drive to appear as two separate drive volumes, which makes it easier to upgrade either component individually.