A 3.5-inch hard drive is a type of data storage device commonly used in desktop computers and servers. The name refers to the physical size of the drive, which is 3.5 inches wide. These hard drives use magnetic disks to store data, allowing for large capacities, often ranging from hundreds of gigabytes to several terabytes. These drives are typically installed in a dedicated drive bay within a computer case. They connect to the motherboard via SATA or SAS interfaces, enabling fast data transfer rates. While 3.5-inch hard drives are popular for their storage capacity, they are generally bulkier and less portable than their smaller counterparts, like 2.5-inch hard drives.