Probiotic bacteria are live microorganisms that are added to foods, such as, in your case, yogurt, because they are believed to be beneficial to our intestinal environment by maintaining a microbial balance. Probiotics may be helpful by overpowering other bacteria present that could release certain toxins or pathogens, thus causing forms of illnesses or infections. Medicinal uses of probiotics have been investigated for some time now and research, though limited, has suggested that certain probiotics do seem to have positive effects on the immune system, may have anti-cancer potential, and may counteract the effects of some bacteria-induced illnesses, such as traveller’s diarrhea. Some other noted benefits of probiotic bacteria may include lowering blood pressure, taking a preventative approach towards colon cancer, managing lactose intolerance (by taking in active strains of lactic acid bacteria), and lowering cholesterol.

Probiotics are the "GOOD" live bacteria in your food. Good live bacteria already exists in our bodies. It is believed that good bacteria (Probiotics) can aid in prevention and treatment of vaginal yeast infections and urinary tract infections. Doctors have recommended probiotics to aid in thwarting off fever blisters/ cold sores as well as intestinal upsets. There are many OTC medications on the market that offer Probiotics. You can read more about Probiotics on this website, http://www.mayoclinic.com/health/probiotics/AN00389

Products with probiotics contain live microorganisms that are said to be healthy and beneficial for the host organism. According to a definition by WHO, probiotics are live microorganisms which when administered in adequate amount can bring health benefit to the host.
The most common microbes are lactic acid bacteria andbifidobacteria that are used as probiotics. They are are included in the fermented food with specially added live cultures in yogurt, soy yogurt, or as dietary supplements.

These are potential benefits brought by probiotics:
1. This will help manage lactose intolerance experience by other people when drinking milk.
2. Helps prevent colon cancer
3. Helps lower cholesterol
4. Helps lower blood pressure
5. Improves immune functions and prevent infections
6. Helps reduce inflammation
7. Improve absorption of mineral
8. Prevent growth of harmful bacteria

Probiotics are live microorganisms which are thought to be beneficial to man and are being called the ‘friendly or good bacteria.’ I do know that it’s beneficial to our health and I do take it too in a form of yogurt, probiotics drinks and more. I am not afraid to take it but I have many questions why I would experience a diarrhea everytime I’d drink or eat anything with probiotics. So according to Wikipedia, here are the potential benefits for probiotics:
1. It may help lactose intolerant individuals tolerate more lactose than what they could have.
2. It may prevent colon cancer.
3. It may help lower cholesterol levels.
4. It may improve one’s immune system function and help prevent infections since it is good and so it would fight against bad microorganisms.
5. It is thought to aid in the treatment of Helicobacter pylori infections (that cause peptic ulcers).
6. It can reduce the incidence and severity of antibiotic-associated diarrhea.
7. LAB and supplements are found to modulate inflammatory and hypersensitivity responses.
8. It may help correct malabsorption of trace minerals.
9. It helps prevent harmful bacterial growth under stress. This has been tested effective on rats being fed with probiotics.
10. It is found to be effective in reducing irritable bowel syndrome.
11. Studies revealed probiotics’ potential in relieving UTI and bacterial vaginosis.
Although all these have not been proven to be 100% effective, I think it’s worth taking probiotics and if one feels uncomfortable after taking it like me who experience diarrhea everytime, I think it’s best to consult the doctor in order to get medical advice.

Simply put, probiotics are good bacteria that keeps the balance in our digestive tract to prevent uncomfortable digestive issues like IBS. I've also heard that it also prevents halitosis or bad breath.

Probiotics can be found on foods, or in the form of probiotics supplements. For more information about probiotics, you can visit this site:
http://probiotics.mercola.com/probiotics.html