To put one thing straight first; Fibre isn't "a speed" or even a topology.

These days, whether running wireless, cabled, most connectivity is based on Ethernet.

In fact, on Fibre you could run Ethernet in 10Mbit, 100Mbit, 1000Mbit, 10.000Mbit. Not only that, you still can and it was quite common, to run other things such as FDDI, ATM.

Best way to look at Fibre would probably be as a physical media through which you can transport many different things (topologies).

Some key benefits with Fibre:

- unaffected by outside disturbance.
- handles very long distances with very low capacity loss.
- can enable extreme capacities in terms of bandwidth.

So, fibre while it is not a speed or a standard by itself, does represent a giant step in connectivity not only by what it is enabling today as a fast medium for data but even more so, it's ability to scale towards immensely higher speeds and capacity by only changing the connected equipment.