A pap test, or pap smear, is a test done to check for abnormal cervical cells. Generally, these abnormal cells are caused by the HPV virus, which is sexually transmitted and very, very common. Getting regular pap tests ensures that abnormal cells are caught early and, if necessary, treated to prevent cervical cancer later in life.
The recommendations for when you need to get the test and how often you need to do it have changed over the last few years. The most common recommendation is that you should get your first pap when you turn 21, and every three years after that unless there’s been an abnormal test.
There is now a vaccine available for HPV that protects against some strains of the virus, particularly the strains that cause cervical cancer and genital warts. According to the CDC, about 30% of girls in the U.S. had received it in 2010. In Canada, about 50 to 85% of girls had received it.
There are many strains of HPV, so an abnormal pap test does not necessarily mean that you'll end up with cancer or genital warts, but because cervical cancer can be treated when caught early, most medical professionals recommend regular pap tests.