What is cervicitis and how do you get it?

DEAR DOCTOR K: My doctor diagnosed me with cervicitis. What is this? And how did I get it?
DEAR READER: Cervicitis is an inflammation and irritation of the cervix, the doughnut-shaped opening to the uterus. (I've put an illustration of the area affected by cervicitis, below.)
Cervicitis is usually caused by a sexually transmitted infection (STI). Most common are chlamydia and gonorrhea. Trichomoniasis and genital herpes can also cause the condition. In some cases, cervicitis may result from trauma, frequent douching or exposure to chemical irritants. Cervicitis often causes no symptoms. When they do occur, symptoms can include pain during intercourse.