We all get tired. Many of us have felt depressed at times. But the mystery known as chronic fatigue syndrome (CFS) is not like the normal ups and downs we experience in everyday life.

Cancers of the colon and rectum together are among the most common cancers affecting Americans, according to the NCI. They occur most often in people over 50 years old. Test your knowledge of colorectal cancer by taking this quiz.

True or false: Colorectal cancer—cancer of the colon or rectum—is the second leading cause of cancer death in the United States.

True or false: More than 200 viruses cause colds.

Find out more about constipation by taking this quiz.

How savvy are you when it comes to questions of health? Find out by answering the following questions.

About half of all pregnancies are unplanned, says the American College of Obstetricians and Gynecologists. But women today have many safe and reliable options to choose from if they want to prevent pregnancy. Test your knowledge of contraception by taking this quiz.

Atherosclerosis, or coronary artery disease (CAD), plays a major role in the leading cause of death in this country: heart attack. Learn more about this disease and a common procedure used to treat it.

Sudden cardiac death is the leading cause of death in adults in the United States. Knowing CPR may help you save someone's life. Learn more about CPR by taking this quiz.

Thirty years ago, few people had heard of Creutzfeldt-Jakob disease (CJD). Today, it has made the news, mostly from its possible association with "mad cow disease." To help make sense of this puzzling disease, take this quiz.