What Does Drive Bay Mean?
A drive bay is an area for adding a drive to a computer. They
come in standardized sizes, the most common being 5.25 inches, 3.5 inches, 2.5 inches
and 1.8 inches. The sizes refer to the actual size of the
discs rather than the drives. Most of the devices for these bays are disk drives, but other
peripherals can occasionally be used.
A drive bay is also known simply as a bay.
Techopedia Explains Drive Bay
Drive bays allow certain peripherals, mostly disk drives, to be plugged into a computer. While disk drives are the most common, it is possible to use other peripherals, including card readers, USB ports, fan controllers and even small LCD monitors.
There are several standardized sizes for drive bays. The earliest is the obsolete 8-inch bay, which held 8-inch floppy drives. The next most common are the 5.25-inch and 3.5-inch drive bays. The earlier 5.25-inch bays were up to 8 inches deep and referred to as “full-height” bays. These bays were common on older IBM PCs and clones. “Half-height” bays, measuring 1.625 inches high by 5.25 inches, are more common on modern computers for optical drives. 3.5 inch bays were first used for 3.5-inch floppies, but are becoming a standard size for card readers. 2.5-inch bays are mostly used for laptop hard drives and SSDs. Even smaller devices can be used with 1.8-inch bays.