What is the mucus-like substance that is always present in the vagina?

The mucus present is produced by the cervix and is a way of detecting fertile times in your cycle. Cervical mucus or fluid can be non-existent or dry, sticky, creamy, watery or egg white-like in consistency. Watery and egg white-like cervical fluid alerts you to your most fertile days during your menstrual cycle. Once you detect the egg white type fluid, you are very close to ovulation. Immediately after ovulation, that egg white type fluid will dry up. Once you detect that change, you have most likely ovulated. (Ovulation cannot be confirmed by cervical fluid patterns alone. Typically a thermal shift UPWARD for three consecutive days will confirm ovulation.) Some great books that discuss natural birth control and other female issues are 1) The Billings Method and 2) Taking Charge of Your Fertility. Both of these books are fabulous. :)