Check out the Wikipedia article for a lot more detail. InfiniBand is something like a cross between a device interconnect standard like PCI and a networking technology like Ethernet, but with a higher-level command set ("verbs") than just unicast and multicast data packets. It's meant to connect compute resources in a very high speed, very low latency, and very scalable manner. It's not something you're just going to bolt into commercial off-the-shelf software, though. If you need the high performance it offers (and can stomach the high cost) in your application you'll probably be working with custom code. It could be used to replace virtually any interconnect method (fibre channel, PCI, Ethernet, etc) but has only really caught-on in high performance computing applications (probably because it's more expensive and less common, as well as being overkill in a lot of applications).