What are dual-purpose uplinks in Cisco?

A dual-purpose uplink is a combination of one 10/100/1000TX copper port and one SFP-based Gigabit Ethernet port. One of these two ports can be used at a time. This added uplink flexibility allows the use of high-density, fibre-uplink based stacks. Dual-purpose uplinks also offer a full-duplex, gigabit-speed trunk for a stack.