[SOLVED] What the heck is a bridge for?

[mavityre]

I am going to get a "free" bridge with my other components and have no idea what I can use if for. Can someone explain what they do and how I would use it?
Here is what they are sending me.
FREE GIFT ITEM
GIGABYTE AORUS 2-WAY SLI HB Bridge (One Slot Spacing) Model GC-A2WAYSLI

Thanks!

 

[delaro]

It's to run SLI... or Two of the same GPUs at the same time. This is a feature that is being slowly dropped and doesn't always work like it should.

 

[BringerOfTea]

it is for running two gpus at a time

 

[rgd1101]

the bridge is free, but another gpu is going to cost extra

 

[Alabalcho]

It's just a piece of PCB with connectors at the end. Costsless that the ink on that page.