Kefir is a fermented milk drink. It is not yogurt, or even much like yogurt.
Kefir is a simple to make, delicious fermented, thickened milk that really does taste good. Good enough to drink plain out of the jar without a load of added sugar and fruit. Kefir is made by lactic acid bacteria, yeasts and a few other goodies. Live cultures.
When I say Kefir is easy to make, I mean it. You put 2 tablespoons of kefir in a jar, pour in a quart of milk, screw on the lid and put it on the kitchen counter for 8 hours. It is done. No temperature controlled incubating. No pasteurizing. No nuthin'.
If you don't have any Kefir to start with, buy a box of 6 packets of starter culture (I bought mine at Hoegger supply in 2006). Forget the instructions on the box, that is there to sell more packets. I put a tiny bit, 1/6 of a teaspoon into a jar (1 quart size is nice) add a small amount of milk (maybe 6-8 oz.). Shake it up, leave it on the counter overnight and it is Kefir in the morning. Drink most of it, pour in a bunch of milk in the jar and leave it out again for 8 hours or so. Now you have a quart. Use it but save a couple tablespoons. Store in the fridge when done making the Kefir.
I have kept kefir going for 2 years at a time (I dropped the jar and ended that run). I have left jars in the fridge for 6 weeks and made new kefir from the old just fine. It is simple. The only time we need to restart the culture is when the jar is dropped, which seems to happen a bunch.
You can also buy Kefir "Grains". I have used them, they were a gift from a friend, but I think it is too complicated. Just save a bit, add milk, leave out, use, refrigerate.
Like I said, it's simple.
I purchased my powder 7 years ago. I gave a 1/2 packet to a friend. I have 4 1/2 packets left after 7 YEARS. My Kefir powder has an expiration date of 2009 on it. I just made a test batch on the open packet last week, using about 1/16 of a teaspoon, and it worked fine. I say about 1/16 teaspoon, because I don't know for sure. The smallest measure I have is 1/8 teaspoon and I have never used enough to 1/2 way fill it. I don't really measure anything in this process. I use any jar around except pickle jars. Anything with vinegar in it like jalapenos or peppers will flavor milk products.
How do you use Kefir? Just drink it plain or sweetened. It needs less sweetening than yogurt. Use it in dressings. I make Ranch Buttermilk salad dressing with Kefir. It tastes much better made with Kefir and orders of magnitude better than the "ranch" dressing slime in the grocery store. In milk shakes and smoothies it requires no added sweetener. I use it in sauces and custards. Kefir can replace cream, yogurt, buttermilk and Creme Fraiche in most any recipe. I like it in a bowl with our own home grown strawberries, raspberries, blackberries, any berries.
The beneficial lactic bacteria that are present in kefir make it easy to digest. Kefir contains yeast cells, which carbonate the liquid and produce a high concentration of B vitamins. Kefir is considered probiotic and beneficial to digestion and general health. Many lactose intolerant people use Kefir with no problems. Most of the lactose is consumed by the Kefir cultures. The cultures' consuming of the lactose and sugars also drop the carb count to around 4 grams per cup.
Watch out for crap sold in the industrial food markets called Pasteurized Kefir. It will lack all of the benefits of the real thing
Do your friends need Kefir? Just give them a small jar with a live culture. Be a good neighbor, give away a few jars.