Good question, pretty simple answer. Douching commonly means rinsing the vagina with water or a special solution using a container, tubing, and a nozzle (known collectively as a douche). In the past, women were advised to douche to prevent pregnancy (when used right after sex), to treat vaginal infections, to wash away vaginal secretions, and to reduce odors.
Douching is no longer recommended for a number of reasons. We now know that vaginas are self-cleaning; they continually regulate their mildly acidic environment. Douching, unfortunately, washes away the healthy bacteria lining the vagina and alters its natural pH level. It can also spread existing vaginal infections to the uterus and fallopian tubes, or can introduce new ones that can lead to conditions such as pelvic inflammatory disease (PID). Last, but not least, douching does not prevent pregnancy. Recommended vaginal hygiene includes daily, gentle washing of the vulva with mild soap and warm water while bathing or showering.
It's also good to note that anal douching, or enema, is used to flush out the rectum; it does not prevent infections, including contraction of HIV. Hope this helps!Alice!