I first had cold brew coffee at Flip Happy Crepes in Austin more than a year ago. It was so good I thought they had put sugar in it, but it was just regular coffee without the acidity. I didn't know it was so easy to make at home until recently. I found these articles and started making my own. It's really easy and tastes yummy.
I put about six coffee scoops of ground coffee in a mason jar then fill it with water, put the lid on, shake, and let it sit from 12-24 hours on the counter top.
Then I pour it through a filter into another jar. (I found this nifty red thing at a thrift store for 49 cents, but I think you could just pour it through a normal coffee pot filter in your machine.)
To make iced coffee, I pour a little of the coffee concentrate in a glass, add some ice, milk, and usually a little honey, then stir.
It makes the most delicious iced coffee! In the mornings, though, I like hot coffee, so I pour some of the cold brew coffee concentrate in a mug, then pour in some milk (or if I don't want a latte, add some water instead) and microwave it. It is much easier for me than making hot coffee.
I make some new cold brew every few days, when I'm about to run out. The concentrate keeps for about a week in the fridge. I don't measure out how many parts milk or water to how many parts coffee concentrate, but it's about one to one, or sometimes a little less coffee and a little more dilution, depending on your taste. You can also buy some kind of contraption that is supposed to make this easier, but this process is so easy, I'm not thinking I need to go out and buy something else.