This help? Yoghurt is made by introducing specific bacteria into milk under controlled temperature and environmental conditions, especially in industrial production. The bacteria ingest natural milk sugars and release lactic acid as a waste product. The increased acidity causes milk proteins to tangle into a solid mass (curd, denature). The increased acidity (pH=4–5) also prevents the proliferation of potentially pathogenic bacteria. In the U.S., to be named yoghurt, the product must contain the bacteria Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. Often these two are co-cultured with other lactic acid bacteria for taste or health effects (probiotics). These include L. acidophilus, Lactobacillus casei and Bifidobacterium species. In most countries, a product may be called yoghurt only if live bacteria are present in the final product. Pasteurized products, which have no living bacteria, are called fermented milk (drink). In the U.S., non-pasteurized yoghurt is sold as "live" or containing "live active culture", which some believe to be nutritionally superior. In Spain, yoghurt producers were divided between those who wanted to reserve the name yoghurt for live yoghurt and those who wanted to include pasteurised products, the Pascual Hermanos group being the most prominent among the latter. Pasteurized yoghurt has a shelf life of months and does not require refrigeration. Both sides submitted scientific studies supporting their claims. The Spanish government eventually allowed the label yogur pasteurizado to replace the former postre lácteo ("dairy dessert"). People who are otherwise lactose-intolerant often enjoy yoghurt without ill effects, since live yoghurt culture contains enzymes that help break down lactose inside the intestine.[1][2] Yoghurt is rich in protein, several B vitamins, and essential minerals. It contains as much fat as the milk it is made from. For women who experience yeast infections, a common cure is the daily ingestion of yoghurt containing L. acidophilus, which combats the imbalance of colonies of the fungus Candida albicans by adding more L. acidophilus. Another method to combat a vaginal yeast infection is the direct topical application of yoghurt, since Candida species are not able to thrive in the acidic pH that topically applicated yoghurt would generally create.[citation needed] Many antibiotics cause fungal problems of the mouth, tongue and skin due to a reduction in the number of commensal bacteria in the gut. Eating yoghurt can stave off these problems before they happen if taken daily after completing a course of antibiotics. Non-sweetened, drinkable yoghurt is typically sold in the West as buttermilk or cultured buttermilk. This is a misnomer, as the drink has little in common with buttermilk and is, in fact, most similar to kefir. wiki - http://en.wikipedia.org/wiki/Yogurt

make you poop a lot atleast thats what the comercial say's

They are generally Lactobacillus bacteria (that made the curd of the yoghurt) & acidophillus & bifidus bacterial strains. These yoghurt are considered beneficial and add to the beneficial flora in your intestines (help to balance the good & bad bacteria that live inside you all the time in a symbiotic relationship). Good bacteria make some of the vitamins we need (vitamin K - which cannot be obtained from food), and help to control bad bacteria by taking all the living space up. It is said that there are many benefits to eating live culture (but there is much research and debate to be had before you could claim this with good scientific backing).

I ran across a recipe for making yogurt out of powdered milk but it said to make sure it had Live/active cultures in it. So, I looked and my yogurt and it said that it had Acidophilus and Bifidum cultures in it. So I needed to find out it that constituted live/active cultures. Now I can play around and see if I can make my own yogurt.