Your body usually tells you when you are in danger—your heart races, you breathe hard, your palms sweat. But when it comes to sexually transmitted diseases, you may not have any warning signs.

Homosexuals and heterosexuals alike are at risk. Infected people can pass HIV on to anyone with whom they have intimate contact. Men can infect female or male partners, as can women.

Chlamydia is the most frequently reported bacterial STD by far in the United States -- and it can cause serious complications and infections for both men and women if left untreated.

Anxiety and physical, emotional, or relationship issues can interfere with a person's or couple's ability to enjoy or participate fully in sex.

Some may want sex three times a day; others, three times a year. There is no "right" or "normal" level of desire. Differing levels of desire are a problem only if a couple can't find a mutually satisfying compromise.

When choosing a method, you should consider how often you have sex, if you are in a monogamous relationship, if you are willing to plan for sex, or want a method that doesn't depend on planning.

Learning about HPV can help you avoid infection and seek treatment, if necessary.

Bacterial vaginosis is a common infection resulting from either overgrowth of normal vaginal bacteria or as an infection with bacteria from outside the body.