In major American cities today small groups of otherwise relatively normal people get together to discuss, and to a lesser extent practice, S/M. But wait a minute --doesn't S/M mean one person who  enjoys deliberately inflicting pain on another person who, for some reason, likes receiving that pain? The answer certainly is yes, but to understand why these people gather to discuss and practice S/M, you first need to understand the difference between the old, traditional mainstream concept of sadism and masochism and the newer concept of S/M that is currently being practiced in a healthy manner. 
 
In the old concept, a sadist was usually someone who enjoyed inflicting pain on a person who had not consented to it, and a masochist was someone who felt compelled to experience the pain though it was usually considered "sick" to enjoy it. Furthermore, these participants usually had a significant psychological imbalance or disorder, and their S/M activities quite often could easily cause long term harm, both physically and mentally. 
 
The people who gather today to form small communities and even clubs devoted to S/M enthusiasts are very different from this old concept. Before discussing this difference though, let's examine the  perception and image of pain. When most people think of pain, they attach very negative connotations to it, and the more negative the connotation, the more likely they are to think the experience of pain is awful.However, in some cultures the stoic endurance of pain has been viewed as a character builder, and consequently in such cultures it is not always thought of as something bad. In a similar vein, in medical "pain clinics" people are taught to change their thinking towards pain so that the "hurt" doesn't bother them as much. Many of these pain clinic patients also report that, as a result of creating a new attitude towards dealing with physical pain, they have made similar attitude changes and corresponding improvements in other aspects of their lives as well. 
 
Another facet of pain is found in the "runners high" which also occurs in some other sports activities. In this type of "high," as a result of exhausting physical exertion people experience muscle pain that causes the body to produce endorphins, which is a natural painkilling response. Endorphins are similar to morphine and produce pleasurable euphoric feelings. They are also a significant factor in why some people can discover pleasure in feeling pain, but there are other factors as well. 
 
Now back to the new versus the old concept of S/M. In contrast to the old concept, this new S/M has come to emphasize the motto of "Safe, Sane, and Consensual." 

This means that the S/M "play" is done in such a manner that will not cause or transmit any long term physically disabling injury or disease. Foremost is the concern with disabling muscle, skeletal or  nerve injury, and the transmission of hepatitis and AIDS's viruses as well as other diseases. Secondly, this means that the S/M play is to be engaged in by participants who are free of significant mental  impairment, whether by psychological disturbance or disorder, or by mind-altering substances. Then each participant must willingly consent to whatever S/M activity that is performed. If during an  S/M "play scene" one person indicates he or she wishes to stop, whether through a prearranged signal or an outright request, then the other person must stop immediately. Of course this requires prior communication--and people who don't communicate well usually don't do well in this type of S/M. (Note: children cannot give a valid consent!) 
 
One element of the contemporary S/M scene is also associated with the safe, sane and consensual motto: respect and tolerance for other people. Most people in S/M communities act with respect towards each other even though they may dislike certain aspects of some members -- this is what is meant by tolerance. Those who don't follow this implicit rule are usually quite effectively ostracized from the group. About the only time tolerance is not shown is when someone engages in activities that are not regarded as safe, sane, and consensual, or when someone expresses hate or hostility based on unjust discrimination. 
 
Something else also occurs due to the growth of S/M communities: their members form close relationships and often these relationships become somewhat spiritual in nature, much as the bonds that develop between "churchgoers" can enrich their spiritual lives. 
 
Another development in this new S/M is the spiritual growth from an individual perspective, whether from that of the giver (the "top") or the receiver (the "bottom"). This spiritual development occurs as a  result of learning greater self-mastery, either in the sense of developing the ability to administer pain in such a manner that ultimately provides pleasure, or in the sense of learning to approach pain as a challenge to meet and come to enjoy. Sometimes these two perspectives will be combined in one person (who is indeed fortunate) in his or her ability to "switch" between "top" and "bottom" roles. 

And sometimes the development of this self-mastery becomes a varying combination of artistic and athletic expression, though it usually would be judged extreme by our cultural norms. But regardless of whether one is a top, bottom, or switch, the accompanying inner growth brings a sense of satisfaction and sometimes real joy. Then when such personal growth is shared with someone of a similar mind in an S/M play setting, and you know you are enriching the other persons psychic/spiritual life, the energy between the two people is multiplied in a synergistic effect known as a "power exchange." This 
synergy is further enhanced when the power exchange takes place among like-minded members of the S/M community. 
 
There are also other reasons why people are attracted to this relatively new style of S/M. Some people enjoy its rebellious quality of going against society's taboos and cultural norms. For many the allure of S/M would be significantly reduced if the majority of people were openly practicing it. But there probably isn't much need to worry about this happening in the near future. And by no means nsignificant, the thrill of doing something that goes against cultural norms, as well as the stimulation of pain itself, can cause the body to produce extra adrenaline that can be very exhilarating. 
 
Furthermore, for many people the practice of this contemporary S/M leads to what many psychologists refer to as "flow." This is a pleasurable and virtually universally sought after psychological  experience in which a person is so immersed in his or her experience that to a great extent the "self" is forgotten and time becomes significantly altered, and the person feels enriched from the experience. This is similar to the flow experience that artists and athletes often experience. And just as extreme sports enthusiasts such as skydivers and motorcycle racers often experience this enriching state of being, so do practitioners of this new blend of art and sport called S/M. 
 
Though this style of S/M may be an extreme in comparison to most of what society enjoys, rather than being "sick," as some people who have narrow minds would call it, it can lead to a multifaceted  enrichment of one's spirituality. Lastly though, safe, sane and consensual S/M is simply fun -- or at least it should be. If you don't enjoy it, you shouldn't be doing it. But if you don't enjoy it-- which is fine, not everyone needs to--please be opened minded enough to allow others the freedom to enrich their lives with it.