For my Citra Citrus Light IPA I wanted to present a naturally clear beer. I did not have any whirl flock tablets when I made it, no Irish moss, and I don't really want to mess with gelatin finings. What is a man to do? Cold Crash It.
This is actually pretty simple you just put your fermenter, secondary fermentor, keg, demijohn, conical, whatever and cool it to the mid 30's. The yeast get cold, they give up and go dormant. That's basically it, Then you bottle it. There should be enough dormant yeast to carbonate the beer once you bottle it.
In practice I've had trouble with this, I can't fit my fermentors into my food fridge. Never fear because you can keg a beer and counter pressure fill bottles. I always forget kegs are cold and hold beer. You can also secondary in a keg and just bottle normally although I imagine this it less than ideal given the ease of leaving the beer in a keg or counter pressure filling.