'Cunnilingus, ‘eating out’ or ‘going down’ on a lover is stimulating the vulva with your mouth or tongue. (‘Cunnus’ is the Latin word for vulva; ‘lingere’ for licking.)
The tongue is a wonderful instrument to give pleasure to a woman: soft, moist and extremely flexible. It offers sensations that fingers, a penis or vibrator cannot provide. For many girls it’s a sure-fire way to orgasm.
Because oral sex is so intimate most lovers only start this activity after they had intercourse.
Research among Dutch high school students (12-18 years old) showed that 12% of the guys and 19% of the girls has experience with cunnilingus.

Basic techniques
Building up
Different preferences
How to stop worrying and start loving it
Variety in movements
The Alphabet method
Hot & cold

Can I perform oral sex when my girlfriend has her period?

See also: face sitting and the 69 position