What are spikes?

I know what crampons are, but not the "spikes" and "micro spikes" that are mentioned on the forums. What are they, when did people start using them, under what conditions, where to get them? Photos?

I have seen folks using a kind of creeper on easy snow (not ice), amounting to wires that wrap around
the boot. I was thinking of getting a pair, but spikes sound better for some of the dirt trails in my area. These trails can be so slick that safety might demand turning around rather than continuing on.

Kahtoola Micro Spikes
These were the first of the traction systems that were less than crampons but much better than instep crampons or things like Yak-Trax (the wires under the feet). There are several similar products on the market today (Hillsounds) that all do essentially the same thing. They're great for hiking on ice but lack the control that crampons give you for steep ice or places where falls are not an option. When people say "spikes" they're talking about these type of traction devices.

Seems to me that most have Katoolas.on the trails. I have them as well and like them a lot.