mkv format

Short and sweet

What is .mkv format?

What can I use it for?

What programs can I use to open .mkv?

And oh yeah I have a Mac...which makes the maze of google on the subject a lil confusing

What is .mkv format?
It is an open source container for multimedia (but just video right now) built by Russians. Since it is open source it provides a simple container for pretty much any video without having to pay for licensing.

What can I use it for?
Pirating shit. Other than that I guess you could make a DVD home video or something with matroska format... :\

What programs can I use to open .mkv?
As with any media format, you just need to find the proper codecs and then any decent player should be able to open your shit. http://packs.matroska.org/

Best use for mkv right now is for anime. Dual Audio, subtitles, and low motion video.