Multipath: Active/Passive, Dual Active, and Active/Active

Although it’s rare in the PC world, multipath I/O is not new in enterprise IT. I’ve been juggling paths to storage and networks as long as I’ve been a systems administrator, and that’s a bit longer than I care to admit. But the proliferation of technologies has made it difficult to understand path management. What’s the difference between “dual active” and “active/active”? Is “active/passive” really that bad?