There are all different kinds of ovarian cysts. The most common are functional ovarian cysts and they happen because women ovulate-so really, every woman has ovarian cysts. Sometimes, the cyst that forms during ovulation does not burst and release an egg, it just stays and can grow and cause discomfort.
They usually don't even cause symptoms, but when they do you'll notice abdominal pain, frequent urination, a change in bowel habits, maybe spotting or a missing period. When this happens, it's best to see your gynecologist and ask that an ultrasound be done. There is virtually never a reason for alarm with cysts, but it's best to be sure and have your gyno send you to have a transvaginal and abdominopelvic ultrasound. Generally, cysts go away after a few menstrual cycles.
Other types of cysts are abnormal, blood-filled, or dermoid (solid). They are usually removed via surgery.
Having ovarian cysts is not like having PCOS (polycystic ovarian syndrome). Some women with this syndrome do not even have cysts on their ovaries.