Oh boy...

Now, I'm probably going to get a lot of this wrong, but here's what I understand from the event(s).

Infinite Crisis is basically a continuation of a very important story called "Crisis of Infinite Earths." This started around the 80s, after a string of very stupid, very childish, very "un-superhero" like stories had tarnished the image of DC's finest throughout the 50s, 60s, and 70s. Crisis of Infinite Earths was a way to wipe the slate clean (sound familiar?) with all of their heroes and to streamline their origins, powers, and backgrounds.

Crisis of Infinite Earths introduced the "Multi-verse", which basically means that there are several parallel DC universes. Something big happened and these parallel universes crossed into each other (sound familiar?) where characters that shouldn't exist did, and others that existed might have been dead or non-existent. This massive collision of universes ultimately resulted in one big "reset" button for the DC universe that in effect retconned nearly the entire DC universe, for example turning Batman from the jolly Adam West version he had become back into the dark, brooding version he is today.

The problem is that this ordeal with the Multi-verse hasn't gone away, and recent events in the DC universe look like they're going to explode into another large scale "Infinite Crisis", with characters from the Multi-verse running in to each other again.

Here's some resources:
Crisis of Infinite Earths
Infinite Crisis
Final Crisis

Couldn't word it better that Garlador...

To be quite vague, I'd say "MKA" but with the DC superheros instead..There's all sorts of little-"big" stuff going on too.

Except Crisis actually had a coherent plot.

Mr. Mind is gonna eat Blaze!!!