Solid-state drive

A solid-state drive, also called a solid state disk or SSD, is a device that utilizes solid-state memory for non-volatile data storage, but appears to the system as a standard disk drive. An SSD is more expensive than the same capacity hard drive for this reason, but boasts much faster access time with no moving mechanical parts.

Adoption by Apple
The first device from Apple to ship with a solid-state storage is the iPod shuffle in January 2005. The first Macintosh computer to be released with a SSD as an factory option for internal storage is the MacBook Air in January 2008. Apple no-longer offers any product with a mechanically spinning internal hard drive, though they are available as aftermarket items as large internal storage for the 3rd-generation Mac Pro or as cheap external USB drives for other models.

Hybrid drives
In 2012, Apple also introduced a solid-state hybrid drive (SSHD) option in Intel-based iMacs in the form of a Fusion Drive, which is Apple's proprietary hybrid of the speed benefits of an SSD combined with the more cost-effective storage space of a hard drive. This option was discontinued from the 27-inch iMac with Retina display in 2020. It was also offered in the Mac mini from 2012 to 2018.

Upgrade options
Users of vintage MacBooks and MacBook Pros from 2012 and earlier can also swap their internal hard drive for a 3rd-party SSD in a 2.5-inch enclosure to gain the speed benefits, limited only by the bandwidth of the SATA connector.

Users of certain MacBook Air (2010 to 2015) or Retina MacBook Pro (mid-2012 to 2017) models can also upgrade Apple's proprietary SSDs through an aftermarket vendor, such as Other World Computing (OWC), or with a 3rd-party NVMe adapter.

Articles

 * The Apple M1 SSD SwapGate is a Massive Overreaction by Attila Vágó at Medium (2021-03-25)