An HBA (Host Bus Adapter) is the interface card that connects a host to a SAN (Storage Area Network). It is an electronic circuit board and/or integrated circuit adapter that offers input/output (I/O) operations and physical connectivity among a server and a storage device.

Presently, the phrase Host Bus Adapter (HBA) is frequently used for Fibre Channel interface cards. Fibre Channel HBAs are obtainable for all key open systems, computer architectures, and buses. Every HBA has a distinctive World Wide Name (WWN), which is analogous to an Ethernet MAC address in that it uses an OUI that the IEEE allocates.

An HBA could be more accurately referred to as a “Host I/O controller.” An HBA and its allied storage subsystems are occasionally known as a disk channel.