For a factual summary of anal sex from Wikipedia:
“Anal sex is a form of human sexual behavior which encompasses many sexual acts involving the anus, anal cavity, sphincter valve and/or rectum. The term anal sex, however, is often restricted to anal intercourse: the insertion of the erect penis into the rectum.
It is a form of sexual behavior considered to be comparatively high in risk, due to the vulnerability of the tissues and the septic nature of the anus. As the rectal mucosa provides little natural lubrication, a lubricant (such as a personal lubricant, for example) is most often required or preferred when penetrating the anus.”
Well, we all know what it is, but the real “ins and outs” (pun intended!) are very individual and personal.
For the uninitiated, here’s a list of 10 golden rules to get you started:
1. Anal intercourse is the least practiced form of anal sex.
There are many ways to enjoy the anus erotically. The most common techniques include touching the anal opening while masturbating or stimulating a partner’s anus during intercourse or oral sex.
Some people enjoy the sensation of a finger - their own or a lover’s - insinuated into their anal opening and gently rotated. Others may prefer the insertion of a dildo or vibrator beyond the anal opening and short anal canal into the larger rectum. Many men, including hetereosexuals, prefer this form of penetration.
Oral-anal lovemaking is popularly known as rimming. The very idea disgusts some people. Others enjoy performing it or allowing themselves to be probed in this special way.
2. Anal stimulation, including intercourse, is not painful if done properly.
The belief that anal stimulation, especially intercourse, has to hurt is a persistent and dangerous myth. Just as pain anywhere in the body indicates that something is wrong, so is the same true of the anal area. With its high concentration of nerve endings, the anus can produce extreme agony when it is mistreated. Yet it can be a source of great pleasure.
When a finger, object or penis is intorduced into the anus, the anal muscles go into spasm, as if fighting off an invasion. Pain will result if the partners do not wait for these muscles to relax. Under sufficient stress they will eventually collapse and the pain subside, unless further damage is done. But, any ‘pleasure’ afforded from this kind of activity derives mostly from the absence of discomfort.
Maximum anal pleasure requires the elimination of all pain or physical trauma from the anal experience. Self-protection on the part of the passive partner involves being ready to say “no” until he or she is ready to proceed. Readiness is a combination of physical relaxation, usually helped along by plenty of leisurely anal touching, and desire.
Occasionally the anal muscles are relaxes, but the passive partner is still not in the mood. Stimulation should mount only in proportion to the degree of receptivity. [click for more via sexuality.org]