Candida is the scientific name for yeast. It is a fungus that lives almost everywhere, including in your body. Usually, your immune system keeps yeast under control. If you are sick or taking antibiotics, it can multiply and cause an infection. 
Yeast infections affect different parts of the body in different ways: 
Thrush is a yeast infection that causes white patches in your mouth 
Candida esophagitis is thrush that spreads to your esophagus, the tube that takes food from your mouth to your stomach. It can make it hard or painful to swallow. 
Women can get vaginal yeast infections, causing vaginitis
Yeast infections of the skin cause itching and rashes 
Yeast infections in your bloodstream can be life-threatening 
Antifungal medicines get rid of yeast infections in most people. If you have a weak immune system, treatment might be more difficult.