What is the use of iSCSI for your storage network? How is it related to SAN?

standard protocol for encapsulating SCSI command into Transmission Control Protocol/Internet Protocol (TCP/IP) packets and enabling I/O block data transport over IP network

Internet SCSI (iSCSI) is a draft standard protocol for encapsulating SCSI command into Transmission Control Protocol/Internet Protocol (TCP/IP) packets and enabling I/O block data transport over IP networks. iSCSI can be used to build IP-based SANs

iSCSI works by transporting block-level data between an iSCSI initiator on a server and an iSCSI target on a storage device. The iSCSI protocol encapsulates SCSI commands and assembles the data in packets for the TCP/IP layer.