Withdrawal is when the man senses that he is about to come, and he pulls his penis out of the vagina. Sperm is not deposited in the vagina, so pregnancy will not occur. If the woman has not had an orgasm, the man can stimulate her in other ways after withdrawal. It works best if the couple has agreed to use this method in advance.
Withdrawal is always an option.
It is completely private. You may be surprised at how effective it is. It is definitely better than no birth control at all. No fluid, or much less fluid, is deposited into the woman's vagina. This means that there is slightly less chance of infection spreading from a man to a woman.