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

Twenty-five percent of all people in the United States with AIDS are age 50 or older. Find out more about AIDS and older adults by taking this quiz.

Cancer can strike any part of the reproductive system, but research has led to better diagnoses, treatments, and a lower chance of death for many of these cancers.

Lips are for ... talking and smooching and eating. Yes, they're important, but do you know how to take good care of your lips? Take this quiz to find out.

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

Every year, millions of Americans roll up their sleeves to donate blood, helping accident victims, surgical patient and others in need. How much do you know about blood transfusions? Take this multiple-choice test and find out.

The last time you visited your doctor for an illness, he or she might have ordered a CBC test to help determine the diagnosis. CBC stands for complete blood count, but what does that mean? And what do all those numbers on the result sheet mean? Find out by taking this quiz.

Gazing down on the spectacular view from a mountaintop can take your breath away. That breathlessness is oftentimes more than just an awestruck reaction to the sights. It can be a symptom of altitude sickness, an illness that can strike hikers, mountain climbers, skiers and anyone who hits the 8,000-foot mark on a mountain.

Lymphomas are a type of cancer that affects the lymphatic system. Learn more about non-Hodgkin lymphoma (NHL) by taking this true-false quiz.

More than a million Americans are infected with HIV, the virus that causes AIDS. Find out more about HIV and AIDS by taking this quiz.