It is called MSM because its chemical name is methylsulfonylmethane. This is a first cousin of sulphur & is related to DMSO also. MSM is a natural substance found in the body, but apparently is another of those things that have declined in our super fertilized agriculture which has a habit of depleting our foods of many of those nutrients that used to be found in adequate amounts in our foods.You can google MSM or the chemical name & learn more about it. I have loved the results ever since I realized how effective it was. I got a number of people interested & they started taking it and found just as great as I told them it was. A lot of those had some post traumatic arthritis. My nephew was unable to get his hands above his head (fractured wrists years ago from motocycle accidents). He started taking it l0 or 15 years ago and still is. He's probably giving some to his horses & dog also. A coworker told me that her husband's back gave him less trouble after starting it. He had fractured his back in a car wreck several years before & was very painful after that. When The ladder I was did a backward flip 2 years, ER xrays said nothing broke, MRI done 2 days later said I had a slight impaction fracture of the distal femur, tibial plateau fracture, and totally unattached AC ligament in the left knee. With a hinged knee brace, a pair of crutches and the race horse dose of MSM daily, I breezed through recovery with only 2 Orudis kt (NSAID) pills for pain. Knee is painless unless I do something like I did approx. a year later. In preventing myself from falling with a big box of books in my arms, I had to do what I wasn't supposed to - I had to pivot on the left knee and without an ACL, you can't swivel or pivot on the injured knee. I think it was my hamstring muscle I got on that one - unfortunately MSM didn't help that much on that one. Other than not being able to pivot or swivel on that knee, the only other restriction I have is to continue to wear the knee brace when waling on uneven ground, so when I go hiking through the woods, I wear it and very thankful that I have it.