It is called anal intercourse if the penis goes into the anus. It is called oral intercourse if the penis goes into the mouth. Touching the penis or vulva with the mouth is also called oral sex. The vagina produces a lubricating moisture before and during vaginal intercourse that protects the lining of the vagina and the skin of the penis. The soft folds of the wall of the vagina allow it to adjust to the size of the penis.
Vaginal intercourse can cause pregnancy.
Touching the vulva with the penis can cause pregnancy, too. During sexual excitement the penis leaks semen that has thousands of sperm in it. Millions more sperm spurt out during ejaculation. Pregnancy can happen if any sperm land on the vulva or inside the vagina. A woman can become pregnant regardless of her position during vaginal intercourse.