Whats yeast infection?

In immunocompetent people, candidiasis can usually only be found in exposed and moist parts of the body, such as:

-the oral cavity (oral thrush)
-the vagina and/or vulva (vaginal candidiasis or thrush)
-folds of skin in the diaper area (diaper rash)
-the nipples while breastfeeding
-the penis or foreskin in men

Candidiasis is the second most common cause of vaginal irritation, or vaginitis, and can also occur on the male genitals. In immunocompromised patients, the Candida infection can involve the esophagus and can become systemic, causing a much more serious condition: fungemia.

Children, mostly between the ages of 3 and 9 years, can be affected by chronic mouth yeast infections, normally seen around the mouth as white patches. However, this is not a common condition.

I was going to answer this question> after reading the ans. that was given> I don't know shoot. This person has the answer!
shut up! little girl!!!
any infection happens when a situation allows the natural bacteria or in the case of a yeast infection the yeast to grow. please see this website as well http://familydoctor.org/online/famdocen/...
it is very informative.